Nvidia shield portable revive

Jul 2, 2018
Hey everyone. I bought a nvidia shield back when they first launched and loved it but I didn’t have a gaming pc back then so I just watched movies and played android games. But a year or 2 later, my roommate stole it. 2018 now and I have a half decent gaming pc so I bought a used shield off eBay. It’s mostly working but the battery life is much shorter and it seems the SOC thermal sensor is dead(it desplays 0 degrees) and the fan never kicks on. So I’m planing 2 thing
1, upgrade the 18650 cells to 3600mah each
2, connect the fan directly to the main power leads from the battery balance charging circuit and add a small external on/off switch so I can power the fan and not let my shield burn up(or solder to the pcb if I can find a free 5v power rail or testing pads so the fan powers up as the system does)

I’m wondering if anyone has had the thermal sensor issue and if a fix was ever found because that would be better than my idea but if not, any advice or thoughts on what I plan on doing. Thanks and hope to hear your thoughts