Hi
Have you tried a different battery?
Also if it is only charging at strange angles it probably has a bad charging port
I had a 3DS that had a dodgy charging port and I found that I could bypass the issue by using the dock
If you don’t have a doc here’s a link to a battery and charging port
Battery
https://www.ebay.co.uk/itm/133870715776?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4j1vehlgrpa&sssrc=2349624&ssuid=0ACG7idPSQ6&var=&widget_ver=artemis&media=COPY
Charging port(this will require soldering)
https://www.ebay.co.uk/itm/185546561468?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=llWM_Z2_R9G&sssrc=2349624&ssuid=0ACG7idPSQ6&var=&widget_ver=artemis&media=COPY
Here’s a disassemble guide too(this will carry you through the different repairs)
[guide|25069|new_window=true]
Hopefully this helps
Any questions please ask
Thanks:-)