What should be my next step?

I’ve replaced the HDD, the board, and the battery(Twice) and I cannot get this thing to boot. When I initially replaced the first battery I was able to get into diag but it died and it will never charge (even though sometimes it would show the charging symbol). After fiddling with it for a while I assume I killed the battery beyond its low charging point so I decided since I got the exclamation point folder icon to try and new logic board. That is where I am now and it is just flashing the apple logo for half a second and will not do anything else. Should I continue to fiddle with this thing or should I just ebay a 5.5 gen and start from there? (I was going to restore it as it was a graduation gift so it has sentimental value but I can always just keep the body around as a paperweight)