Error The main thread is blocked

I have been using an up 300 for about a week with some pretty good results, however yesterday things stopped working with the error “The main thread is blocked”

I saw a post here before that said to try to restart after receiving the above error
after restart received the error “Internal USB connection error”
and after another restart and initialization “Initialization printer failed”

Another subsequent restart and i can get to the point where I can extrude some filament then the machine dies and the screen comes back with “The main thread is blocked”

Any help? or does the machine need to go back for service?

PLease contact your reseller or, you may need to change the PCB with the USB port on the back of the machine. This could be done by you or your reseller. Sorry for the problem.

Thank you for your reply, I have talked to the re-seller, he got me to unplug and re-plug cables on that board then confirmed that it will have go back and have the PCB replaced.

Thought I should update you guys here.
The problem ended up being the CPU, it was overheating and when it overheated it stopped communicating with the display board - and hence the errors.
Tiertime were very patient in working through this to get to the problem and I appreciate the support.
The Up300 is back to printing awesome results in ABS.