"I read somewhere on the net, the karma drones issues happened because the battery popping out a bit, and there are suggestion to use like sellotape or duct tape to fix that"
"This is in my opinion the best auto pilot vor beginners Jimmy Underhill said:
Go for a Pixhawk based system instead of APM. Much better hardware, the APM is known to fail prematurely and isn't as powerful.
The RCTimer Fixhawk is a good clone."