Switch Lite - No display after failed Picofly install

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Hey all, I have an issue with a Switch lite. After installing a picofly, I powered on to test and saw a puff of magic smoke but I couldn't pinpoint where it came from. I immediately powered down the system to check for damage and didn’t see any burned components, but I noticed the lcd driver (8316 chip) was cracked in the corner. I replaced the 8316 chip but no dice, so I started checking voltages and one of the test points near the lcd driver measures 1.8v (normal), but the other measures .5v. From what I've read, this is the point that connects to the SOC and it's supposed to supply 1.8v to enable the lcd driver but it's low so the lcd isn’t even being told to turn on. I think these voltages stem from the MAX77620h chip on the back of the board, but not sure. Where would be a good place to begin to troubleshoot this? Or am I completely screwed here?


Note: The system DOES power on and the backlight, sound, and touch all work fine. I can hear the system sounds while scrolling through the home screen, but I just can’t see anything lol. I have uninstalled the modchip to rule out the possibility of improper or bridged solder joints. I’ve also double checked the screen fpc connector and ribbon cables to see if there were any bent or scorched pins, but all is well. I've done 4 Switch lite picofly installs in the past and all went fine, so not sure what happened here. Thanks in advance for any guidance.
 
Have you checked with a strong flashlight if the LCD screen itself is working?
The screen is almost directly connected to the CPU so there usually isn't a problem with voltages.

The backlight circuit is something that can go bad as it is way more power consuming.
If the Switch faintly glows black in a dark room, then probably the backlight is fine.

Another thing to check is the LCD connector for damage (missing or bend pins).
It's surprising fragile and I do get Switches with just broken connectors from time to time to repair.

For more power checking, refer to this write up :
https://www.retrosix.wiki/full-boot-from-bench-power
 
Thanks for the reply, but as stated the backlight works fine and the fpc connector is good. Actually I just resolved the issue. There was a resistor that must've gotten knocked out of place near the 8316 chip. I flowed it back into place and now the display works, but none of the buttons work except for the home button, and the touchscreen seems to have dead spots. This thing is becoming a nightmare lol. I think the STM32 chip on the back is responsible for the buttons so I'll check that out, and will check to see if the touchscreen cable and connector for any issues.
 
Thanks for the reply, but as stated the backlight works fine and the fpc connector is good. Actually I just resolved the issue. There was a resistor that must've gotten knocked out of place near the 8316 chip. I flowed it back into place and now the display works, but none of the buttons work except for the home button, and the touchscreen seems to have dead spots. This thing is becoming a nightmare lol. I think the STM32 chip on the back is responsible for the buttons so I'll check that out, and will check to see if the touchscreen cable and connector for any issues.
What's new ?
 
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