[SOLVED] Various issues with my build (from a beginner)

[Nystagmus]

Right now,when the FM2 starts up, the OLED display shows only squares. I haven't managed to get a good connection between the header and the display, using only the provided spacers.  Instead I have to add a pair of additional spacers, without these the display doesn't light up. This might have something to do with how I attached the low profile header. I tried to follow the instructions, but maybe the header wasn't attached correctly. I became a bit unsure about the perpendicular placement.

Also, I am not very experienced with projects like this, so I made a couple of mistakes. Somehow I was able to damage the upper pad of the second 1 M resistor, the one next to the 68 ohm resistor. After looking at the Kicad file (which didn't seem to show a very similar version of the PCB, although not identical to the one I received in my kit) I soldered the upper pin of the second resistor to the bottom pin of the other 1 M resistor. Was that correct?

Finally I think I have some issues with the ICS and the DIP sockets. The PreenF405 was almost impossible to fit into the socket, so the "socket part" connecting to PB7 was damaged, I am not sure if the connection works. Some of the legs of the other ICs became very loose when I tried to straighten them up and fit them into the sockets, so I think there are issues there as well. I actually was able to get mumbo jumbo characters as well as a frozen startup screen form times to times when I tried to make the ICs fit by pressing them down and taking them out and put them back again...

So, a lot of problems to solve. And yes, I am a beginner that made a lot of stupid mistakes. But I would be extremely thankful if you could tell me how to proceed in the troubleshooting.

[Xavier]

Right now,when the FM2 starts up, the OLED display shows only squares.

This happens when the preenF405 cannot read from the USB stick.
Is your USB stick in place, freshly formated and contain the "/pfm2/"  (with the preset files inside) ?
Do you see something different when you press one of the buttons while powering on ?

I haven't managed to get a good connection between the header and the display, using only the provided spacers.  Instead I have to add a pair of additional spacers, without these the display doesn't light up. This might have something to do with how I attached the low profile header. I tried to follow the instructions, but maybe the header wasn't attached correctly. I became a bit unsure about the perpendicular placement.

Sounds like a bad soldering point. Spacer should not have any impact on the connection.
The connection should be solid, so you can modify a little the angle.

Also, I am not very experienced with projects like this, so I made a couple of mistakes. Somehow I was able to damage the upper pad of the second 1 M resistor, the one next to the 68 ohm resistor. After looking at the Kicad file (which didn't seem to show a very similar version of the PCB, although not identical to the one I received in my kit) I soldered the upper pin of the second resistor to the bottom pin of the other 1 M resistor. Was that correct?

Yes sorry for that, i uploaded yesterday the R5 version of the PCB.
I attached a screenshot with the 1M resistors.. .Seems like what you did is good.

Finally I think I have some issues with the ICS and the DIP sockets. The PreenF405 was almost impossible to fit into the socket, so the "socket part" connecting to PB7 was damaged, I am not sure if the connection works. Some of the legs of the other ICs became very loose when I tried to straighten them up and fit them into the sockets, so I think there are issues there as well. I actually was able to get mumbo jumbo characters as well as a frozen startup screen form times to times when I tried to make the ICs fit by pressing them down and taking them out and put them back again...

I flashed all preenF405 by puting them in a DIP40 socket. Some of them are harder to insert than other but none are impossible 
This one sounds like the most serious problem, but you're lucky :  PB7 is one of the few pins that are not used.
You should get the R5 files here :
http://ixox.fr/preenfm2/download/
And check with the multimeter your connections from the preenf405 to other side of the PCB on the DIP40 socket soldering points (gently remove the OLED, the low profile headers are fragile, try to remove all pins at the same time so that none of them blend).
You'll quickly check which pins are correctly connected and which pins are not.

So, a lot of problems to solve. And yes, I am a beginner that made a lot of stupid mistakes. But I would be extremely thankful if you could tell me how to proceed in the troubleshooting.

Yes a lot to solve but i'm confidant it will work.
Let me know your progress.

[Nystagmus]

Thanks a lot for your help. You have no idea how worried I was about not getting the synth to work, it was like having a sick child  . Anyways, I asked a friend for help, he just happens to be a civil engineer so it took him about 1 min to fix the synth. Two of the solder joints needed more solder. One of them was at the display header, just as you expected.  And I had to replace the usb stick. Maybe you should add some info about the "squares in the display" error to the build instructions?

Right now, my only issue is that there is almost no white color on the top surface of the case, you can't read the text on top of the tacs and knobs. Is that a common problem?

I don't think fitting the ICs are hard at all if you have some idea of what you are doing. I am more of a Tim the Toolman Taylor. Btw, I really love this little synth, it sounds great and changing parameters was much easier than I expected.
 

[Xavier]

Awesome, i'm glad it works 

Sometimes it's enough to just reformat the USB stick and to extract again the /pfm2/ directory on it.
It's already in the FAQs - sticky subject of this board
I've just editedto make it clearer.

Yes the plexy engraving does not really change the color. It's common to all enclosure made with this method.
You can paint it or play more with your preenfm2 so that you don't need to read the labels anymore 

Xavier