Siglent spectrum analyser baffling behavior - power supply ???

[Mike Jung]

My son's has a 2nd hand Siglent spectrum analyser SSA 3021x - I think...  This machine behaves as follows :

Pushing the power button the "machine" seems to want to start and two other keys light up on and off, or rather their intensity varies every two secs or so. Nothing more happens, the machine does not start.

HOWEVER, if one removes the fuse, looks at it and places it back the machine starts and works perfectly including of being started and stopped for a few hours. Next day, back to square one.

This is beyond baffling and I wonder if anybody has any idea as to what could be happening.

[m k]

First something overloads something else, varied intensity implicates that power supply tries to start but fails and tries again.
Removing a fuse set input energy level falling and at some point it's not overloading anymore and remaining energy actually loads that overload something away.
Until long enough time drains that something and it start overloading again.