White Screen After installing L2/R2 Addon

[01010111]

I originally ordered a CM3 with the brightness control preinstalled. It worked perfectly. After I learned about the add on board for L2/R2, a temperature controlled fan, and joysticks I ordered that.

I’ve finished the installation of the physical components and I’ve modified the case so everything fits. But now I only get a white screen when I try to turn it on. It worked perfectly before the add on. I’ve gone through the steps on the troubleshooting page. I’ve reinstalled the retropie image. I unplugged and replugged the CM3 to make sure the connection was tight. Still, I get nothing but a white screen when I try to turn it on. No LEDs when I try to boot. The battery controls all still work, too.

What else should I check? I’m beginning to think I bricked it... 

[Porcinus]

It can be many thinks:
TFT ribbon cable moved (really hard to see by eye): disconnect and reconnect it.
Wrong soldering, 5v or USB+ short with something.
Wrong connection on compute module or sdcard : disconnect, blow air and reconnect it.

Does it work back if you unplug addon board?
Problems occurs right after 'physical' modification or software modification?

In my setup, if addon board is not plug all the way, I have some I2C troubles, sometime not able to power the system.

[Flavor]

I would also try removing the brightness controller (just keep the 2 wires connected and remove the ribbon portion). Then see if everything works. Unfortunately, the brightness controller ribbon cables can get damaged somewhat easily. If this "solves" your problem, let us know by opening a SUPPORT inquiry at http://www.freeplaytech.com/contact/

[01010111]

I would also try removing the brightness controller (just keep the 2 wires connected and remove the ribbon portion).  Then see if everything works.  Unfortunately, the brightness controller ribbon cables can get damaged somewhat easily.  If this "solves" your problem, let us know by opening a SUPPORT inquiry at http://www.freeplaytech.com/contact/

The screen seems to work fine after disconnecting the brightness controller. So, I’ll definitely open a ticket. 

After some additional testing I was able to get the L2/R2 buttons working as well. I think at this point 90% of what I have to do is in the software.