Even if the thermal protection circuit is tripped, you would have had to reset it before the motor came back on.
This is often caused by debris build up in the pump shaft housing, Or the motor is otherwise obstructed in some way, causing it to heat/seize.
The pump shaft housing is easily removed and cleared.
If that does not do it, you will need to lubricate the pump motor it self. One - two squirts of lube spray (we like PB plaster) will do.
Opening the housing is a bit more challenging but there are details instructions on our manual section
www.jobo-usa.com/resources/manuals
The motor might also have a corroded shaft, which might be beyond repair, you will only find that out when you open it up and have a look.
Good luck.
Let us know what you find.