2020 SR5: how to test stock amp

Hoping someone can help me out. I understand electrical, but am a dummy to audio stuff.

I picked up a 2020 SR5 DC this past week from a dealer 4 hours away. Drove home fine, but i noticed the radio sound was terrible, but i mostly just listened to podcasts. I got home and started messing with it more, the only sound comes from the dash speakers. The door speakers aren't playing along. I messed with the fade and such, confirmed this. When i turn it to full rear, sound goes completely away, etc. Same using FM, car play, etc.

So, i've read the dash speakers are powered by the head unit, door speakers are powered by an amp under the seat? I checked the 30 amp Amp fuse under the hood, verified it is good. My next step is to check the amp itself and the connectors. Can i just check for power into the amp then power coming out somewhere? I can't imagine the stock amp has any lights on it. Any fuse on the amp itself? I have a Fluke multimeter, just need to know what to check for and where...

I'm hoping someone pulled a plug on it while vacuuming it or something.

 

The connectors won't just pull out from vacuuming around it. The amp is under the passenger seat so it's easy to get to. You can trace the wiring diagram to see if there are any additional fuses. The stock audio is crap in general but I haven't heard of any amp failures. Pull a door panel and see if they are stock speakers.

 

Update:
While testing the fuse, i removed it from the fuse panel to check for continuity. It checked good so i reinstalled it. I looked under the passenger seat to verify the amp was plugged in, gave the wires a little wiggle, all tight. Checked the radio again and all the speakers are working! So who knows... maybe it reset when i pulled the fuse? Maybe the fuse wasn't fully seated?

 

Could be a short/loose connection with the amp plug since it worked after wiggling it.

 

I was about to suggest to try throwing it away. I installed a new headunit and bought a bypass harness that basically cuts that garbage amp under the seat out of the picture. Now my Kenwood headunit powers everything instead of the the amp and it sounds so much better. It even has some decent bass with everything else left stock.