But before it used to drop another board after been mining for a wihle. So there migth be another bad soldered Heat sink missbehaving when heating up
Yes, that is exactly the cause, one or more heatsink are not glued perfectly, sometimes they will contact and read and sometimes they don't, I have a few boards that behave this way, just mine with it until it longer functions, the bad heatsink will eventually fall off or at least becomes so loose that you can identify it with your bare eyes/hands.
I will try to contact their support to see if I can get in contact with someone from Poland.
go to this page >
https://www.zeusbtc.com/Repair.asp, scroll down and you will see a list of some cities/countries, looks like you have to keep your contact information and they should contact you.
The site also mentions
Attention: The miner repair points shown on the map below are independent individuals. This site only offers a free display. Please contact the maintenance point for specific matters. If there is any dispute, please resolve it by negotiation. Any consequences will not be related to this site.
So it doesn't seem like they are a branch of Zuesbtc, but I can only assume that Zeusbtc must have done at least a basic check on these guys to confirm their integrity, some of them might have got some training in China from Zeusbtc, I tend to think that they can be trusted, but I would still. deal with caution
is EU based and reliable (bougth a miner back in 2019), more expensive then most of asian sites, but if you do your purchase trough a company they will deduct the tax. They have both miners and spares availble, mostly on request though. I dont know if tare afiliated with Bitmain, or not.