You are right there is something wrong, very often dealers do not have the specialized technicians to do electric/electronic diagnostic work, they can swop parts, but not really diagnose.
Do you have and independent shop that specializes in auto electrical/electronic work? If you do go there even if you have to pay for it. Once it's diagnosed you can go to the dealer for the warranty work.
This is what I don't like in modern vehicles, way too much electronics.

 

Canadian tire has good choices of batteries. We have two Lexus dealers in Calgary.
Lexus of Calgary and Royal Oak in the North West. Out at Ogden road SE there is a
battery shop who sells brand new but some blemishesd(scratch on the case like that
functionally nothing wrong with a full warranty) I always go there if I need battery.
Had good luck with Magnum brand.

 

What do you think of this one? I am going to pick it up in a little bit here.

https://www.canadiantire.ca/en/pdp/m...3420p.html#srp

 

I am just going to buy a new AGM one. The one in the Lexus is acid anyways right? I might be wrong lol

 

I think that the 2017 Lexus is an AGM.
I'm not a fan of canadian tire batteries, they are not as well built as others (top tier}, they exchange them for free and I think that after a certain time they charge you only for installation, but it's PITA to go and have them exchanged. Batteries is one field that you get what you pay for. Depending on how long you keep the vehicle or whether it's leased or owned, that would guide me in the purchase. One word of caution, AGMs don't give you any warning when they fail, one day they are good the next day they are bad, not like the old acid ones.

 

 

Haven't bought batteries at Canadian tire for decades, things may have changed, but in the past they were batch manufactured by various makes up to Canadian tires specs. The cells had thinner walls and there was less lead in each cell. That was my experience.

 

 

I wouldn't hardwire it, but use a plug-in for the socket so that I may unplug whenever not in use. It could cause a drain depending on how it was connected.

 

 

There may still be a draw. These days with all the electric/electronic stuff it's a nightmare to diagnose.

 

 

I have a thinkware f800 pro hardwired as well for parking mode. It shuts off automatically when the voltage is under 12.3 and also after 6 hrs. This on top of all the sensors etc can definitely kill a battery.

When as the last time you drove the car?