2017 XM reception suddenly degraded

Hi all,
This is my first post after lurking a while. I have a 2017 TRD OR DCLB, original owner, essentially stock. I have always had Sirius XM and it has worked fine. Recently it just degraded to crappy reception. I have tried re-setting the connection according to XM instructions but it did not help.

About the same time I noticed the change, the truck had been at the dealer for a recall-type thing with the 3rd tail light. They said water can leak in so they wanted to install some fix and I let them. I don't know for sure that's when it degraded but it was within a week or two of noticing it.

I'm attaching a pic of the antenna wiring route; it seems likely that perhaps they crimped or disconnected the wire? Upon return to the dealer they say what they did to the 3rd headlight was from external only and would not have impacted the antenna wire. They want $200 to look at it.

Has anyone here had this happen? Is there a way I can diagnose whether the antenna is actually connected and/or has good signal? (The AM/FM seem to be fine)

I don't really want to give the dealer $200 to look at it. it'll end up costing me $1000 if I let them touch it. Is opening up the headliner easy to do and not screw up? Is that even how I access the wire? I'm pretty good mechanically but I'm afraid I'd ruin the cosmetics or perhaps damage the headliner. If anyone has any experience or instructions they can share it would be greatly appreciated!
Thanks.

 

This thread may be helpful.

https://www.tacomaworld.com/threads...shark-fin-with-a-oem-satellite-stubby.552228/

 

Thanks for that link! Great info on removing the headliner.

 

I'd just go tell them that after they did the brake light work your XM reception went bad and they need to go fix it right. I'm betting they messed something up.