Lite won't turn on, where to start?

Hi all,

I picked up a broken Switch Lite from the side of a road. The unit was missing a digitizer and LCD and had a broken joycon daughterboard amongst other damage, so I bought all those parts to see if I could fix the unit. The motherboard appears to be in almost perfect condition, with no traces of water or physical component damage, which is the main reason why I thought I could give it a try.

However, the display doesn’t turn on when I try to turn it on with the power flex cable. The fan doesn’t spin either, but I can feel the CPU area getting warm/hot. Occasionally, the blue LED under the home button lights up. The battery doesn’t seem to properly charge through the USB-C connection, but I can charge it by directly connecting the battery to a bench power supply. When charging through the USB-C port, it draws 60-70 mA @ 15 V.

Any idea where to start or find diagrams/reference voltages? I tried checking the MT and BQ chips for shorts. I didn’t find any, except for the gray component circled in red, but I’m not sure what that’s indicative of.

I’m having trouble uploading images/links, but I can try to provide more pictures if needed.

Thanks in advance!