Playstation 1 fat freezes before dashboard

Hi,
I got a ps1 some days ago that do not load the dashboard and it freezes at the Sony logo.
I took apart the console and there isn't any modchip and everything looks in quite pristine condition.
Any idea how to fix it?

 

Try unplugging the laserassembley and check if it boots. I not, find a modchip diagram for the model and start to look for previos microscopic misses from earlier work.

Other than that i dont know

 

Thank you for the reply. I tried to unplug the laser (and also the controller) but nothing changes.. There isn't a modchip installed >.<
It's my first time to have a such issue.. quite weird and uncommon I guess

 

Still iv have had playstations mainly psones (slims) look fine, but under the magnifying glass there have been bridges on chips and missing smd caps on the common modchippoints.

 

OK, I will have a look! Thank you

 

Just a small update, the ps1 is a PAL scph-5502 PU-18 pcb.
I was looking carefully and I found a little bit of oxidation in a smal point.. a cleaned up and I took a pic..
is there a component missing (that is the left upper side of the pcb)?

 

dont know about the components, id hav to check. But that via needs patching. A small wire maybe?