Southpark:
Sounds damaged.... especially since you're getting well below the usual voltage.... and puffy battery. Time for a new one. Also helps to have spares.... and maybe need to have some kind of current monitoring or current limiting system to avoid drawing too much current from the battery.When it comes to rc and batteries.... have spares on hand. And check on power handling specs to try cut down on issues. Sometimes the issues can be due to quality issues. Hard to say what happened right now.
Does that mean I may have to add BECs for current limiting. May be you're right about drawing too much current. Coz it hikes up on 50% + throttle too making quad unstable even if pids are reasonable.
Thanks though.