Line 6 DL4 sound only in bypass mode

[Flux]

Hey! Im trying to repair a Line 6 DL4. When I got it, the device was completely dead. I checked most of the components and replaced some broken diods (D11 & D16).
Now its powering on, and buttons and lights work as they should, but there is no sound when I play my guitar through it. I tho get a signal when the device is in the chain but turned down (bypass mode).
I already tried most fixes that I found on the internet. I have a multimeter but have only been checking for Ohm. Can you give me some advice on how to troubleshout for that issue?
Ill attach the schematics on here. The first part is the DL4.
thanks in advance!

[The Dude]

Since the diodes you replaced were at the supply input, I would start by checking your power supplies and see that they are working (3.3V and 5V). Are you using the correct power supply (9VAC)?

[glebert]

I would use your meter to check and see if all the voltage rails for the op amps and the digital chip are at the expected voltages. After that I would probably look at the relays (U8 and U18), see if they are getting the right control voltages for bypass vs effect and then if they are in fact making connection for the effect mode. You should be able to do that with the ohm meter.

I've seen a bunch of these being sold for repair but couldn't find a schematic or any record of someone fixing one so I always passed.

[Mick Bailey]

There's a factory test procedure that uses the LEDS and switches to verify the circuit operation. I have it on an old hard disk somewhere but it would take some time to get running. PSU issues are fairly common. I've also fixed a few of these by reseating the main processor.