Melitta Caffeo CI 970 101 goes out again and again

Hello to all

I have a problem with my coffee machine.

Type Melitta Caffeo CI 970

I had the machine up today because I suspected that the pump of the milk frother was defective.
If I
wanted to
make milk foam
I had to hold up the pack of milk

so that the milk

runs

almost by itself into

the hose because the pump did not manage to suck the milk any

more

.
I reassembled the machine and now
there's this problem.
If you turn it on now, it will go on and off by itself after about 3 seconds
and all the

time, you can only stop it by

pulling

the mains plug

. Has anyone ever had
that problem before
?
Thank you

Did the switch get jammed during assembly...????? so that it is now constantly bridged...