Used iPod 5.5 from ebay gets hot

Hi,

I bought a used iPod 5.5th Gen. from ebay and the seller said that the battery would be dead.

When I opened it, i noticed that it doesn't look quite good from the inside. The lcd connector has green sediments and especially in the lower right area of the mainboard, some pins of those chips/resistors don't look very well (brown-ish).

When I connect a new battery, the iPod got warm and then hot quite fast so I immediately removed the battery cable again. I tried to clean everything with Isopropanol.

Is it safe to try to connect the battery again? Or can it somehow explode or catch fire?

https://preview.redd.it/80k29lnmolzg1.jpg?width=1608&format=pjpg&auto=webp&s=a574db0e5c5b5c03a57c064b05cb2e0c9da2e306

https://preview.redd.it/563rxknmolzg1.jpg?width=1608&format=pjpg&auto=webp&s=0f840b8b71c434bbfe11c4694923cbd0357dc433