Subwoofer causing Hybrid Failure

I have a 2020 Prius prime. Stock stereo. I upgraded it adding separates in the front and disconnecting the rears. I have a DSP under the passenger seat and a five channel amp under the drivers Seat. The fifth channel runs to the rear hatch where I have an Audison 8” passive amp enclosure.
Last week I started getting dashboard warning lights telling me that the hybrid system as well as all the safety features such as lane departure were malfunctioning. And, indeed the hybrid system was not functioning.
I took it to my Toyota dealer, and $600 later I am told that the magnet from the subwoofer was impacting the heating and cooling systems of the hybrid battery. I don’t know if this is accurate or not and I guess time will tell. The subwoofer has been disconnected. I’ll see if the problem happens again. I do notice water in the charging port after rain. The dealership said this would not be causing the problem. Again time will tell.

Has anybody else heard of anything about batteries causing troubles with the hybrid batteries?

 

I could’ve been more clear, the subwoofer was a quick disconnect now sitting on the backseat, not connected, and I’ve had no reoccurrence of the issue.

 

I understand the perspective of putting a dummy load on, and I like that idea. I’m just gonna sit tight for now and just use the fronts with no sub. I have Hertz Millie Legends, Hertz DSP and an Audison 5 channel amp.