[solved] Preenfm2 r6 new build problems (screen blank, blue led blinking?)

[Jverchot]

Hi!
I have assembled a preenfm2 R6 using this screen: https://www.tme.com/us/en-us/details/rec002004abpp5n01/alphanumeric-oled-displays/raystar-optronics/rec002004abpp5n00100/
I'm very experienced with soldering, and I found all of this to be a breeze.

I managed to get windows 10 to see it as a stm32 device by going to device manager, telling it to look in the DEFUSE folders for the drivers, and installing them.
sucessfully used defuse to "upgrade" the pfm_2_20.dfu, also verified it.

so when I take the boot jumper off and power it on, the blue led on the back lights up for a second or 2, then blinks every 2 sec or so... BUT

the screen is black, does not flicker, light, or do anything.

no idea where to go from here.

[Jverchot]

ahhhh!!!!

there was the TINIEST solder debris bridging pins 12 and 13! and now it comes on! I didn't try that after wrestling the bootloader/firmware for hours and hours yesterday morning...lol.

[Xavier]

Thanks for the update