MK180 Problem: not flashing

Hello forum,
about a year ago, I assembled the very nice mini kit MK180.
Now, it stopped working. When power is applied, one led group is flashing, and the other is lightning continuously. This behaviour is not consistent. Sometimes, nothing is happening, or just a short flash of one of the led groups. Pushing the small button gives no result.
What can I do to make it work again? I already checked the soldering points (kit is used on a quad) and cable connections.

Total work time is about one hour (!) on a quad but in a appropriate housing.

Thanks for the help!

Most likely there is a mechanical problem (e.g. bad or loose contact, bad or loose soldering, etc…).

What can I do to check. All soldering points seem to be ok. Should I try to reheat so the solering is melting again? That looks dangereous to mess up the kit.
Is there some documentation where I can find some checkpoints to measure (voltage, resistance)?
Or is there some kind of guarantee service that can verify the components?

You can return your kit for inspection to:

Velleman Kit Tech. Dept.
Legen Heirweg 33
9890 Gavere