Hello,
I had exactly the same issue and fixed in in about 30 mins, without spending a penny!
• Disassemble gamepad - fairly easy, just take your time and be gentle with connectors
• Take out main motherboard - this is the one everything is plugged into, held in by silver screws
• I then used a hairdryer to heat the board, focussing on connection points, chips and other components.
• Reassemble carefully
Once I reassembled, it worked straight away and has been fine since!!
Hope this helps someone.
Stephen