Need help, ROG ally won't turn on but accepts charge?

Got an item for spares and repairs, the back plate is a tad knackered and figured it'd be an easy fix because the case crack is over the battery.

The orange LED turns on then flickers for a bit.

Opened up the case, taped over the light sensor and unplugged the battery, the orange light still turns on but stays on longer and flickers before stopping

There's a light buzzing sound coming from somewhere when attempting to turn it on? I'm assuming charging.

APU cover remains cold?

No fan activation