Sport cub S servo goes insane

[FieldRC]

Hey guys,
When I do a rough landing with my Sport cub S the servo/elevator servos on the RX/ESC brick just go crazy. They twitch uncontrollably, and I'm afraid they will eventually get fried.
There are some things I think are related.
The light on the brick only flashes red when it isn't bound, before there was a blue light. Sometimes the plane doesn't turn on at all and I need a few tries inserting the battery.
The plane sometimes has a hard time binding.
The normal blue/red only flashes once when I insert the battery
Sometimes only the flaps work, the motor needs several secs/a second try with the battery to get working
I replaced the batteries of my TX, but it still might be a receiver problem, since I did fiddle with that wire thing in the terminal.
More likely, there might be a problem with the female plug or soldering to the board.
Any ideas, or similar experiences with this plane (or similar)?

 

[LitterBug]

Sadly, your main board may be on it's last leg. My Sport Cub S died a different way, it got run over and chewed up flying at indoor flying events. I'd look closely at the power plug, batteries, and where the power connects to the FC. The connector itself is not very robust, and I've had to replace the same connector/batteries for my tiny whoop because the connection is bad.