It seems every hardware thread has at least one member replying, "have you checked the battery"? In this thread it will be me

Have you checked the battery? It's close to the 68000 (lower right from the front) and can damage the stock CPU and related things. As the CPU slot is next to the 68000 it might be that the motherboard is damaged...
Do you have an opportunity to test the PPS card in another A2000?