Hi @RozAnd,
We recently had an issue where some Pixhawks had faulty overcurrent protection on the output lines, which had the same behaviour you’ve outlined here. Assuming both the Pixhawks you tried were purchased reasonably recently, then presumably you’ve had the misfortune of getting two faulty ones from before we found out about the issue and started actively checking for it.
I’d recommend you contact support@bluerobotics.com, and link them to this thread. They should be able to provide you with a replacement Pixhawk that isn’t faulty. It would be helpful if you can include the order number/date from your initial purchase(s) 