2019 CX-9 wouldn't start and bunch of malfunctions

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2010 CX-9 GT
LiFePo4 batteries.
AGM weight more due to the thicker plates usually.

Deka, Optima, Braille, Odyssey, and others make AGM batteries that are 20-30% lighter than the traditional flooded batteries. It's a relatively cheap and easy way to save weight if you are scrounging to save every pound (think race car here, it's of marginal use on a daily driver).

Other, even lighter, battery chemistries are available as well, but are a lot more expensive.
 
Quick update. Took the battery to Autozone they tested it and it's at 0. Got a Duralast Gold from them and now the car starts again.
Did this solve all the other issues as well? I test drove a 2016 CX-9 today and it had all the same malfunctions, the salesman said the battery had been dead. I'm hoping just replacing the battery would solve all the issues because I really like the CX-9.
 
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2016 Mazda CX-9
Hi everyone,

Sorry English writing is not my strongest skill.

Rough day today. Spent my afternoon detailing the 2019 CX-9 (bought at Nov 2018 now 37k miles just passed warranty) and in the end the car wouldn't start. Everything was normal before the wash. It was throwing a bunch of malfunctions including SCBS/Keyless System/Cameras/Sensors etc I couldn't remember all (And one says Refill the tank but I have 4/5 full tank). Basically most of the dashboard was lighted up. It did try to crank for half a sec and stopped. I used Torque Pro app and BT ODB2 adapter and no fault code found. I'm suspecting the battery is dead but car is only less than 2.5 years old. We do daily 40 minutes each way commute and some short trips.

Here's the list of my diagnosis I've tried / things I did / possibilities.
  • Fortin Evo-One with Maz3 harness was installed 2 days ago by myself and was working flawlessly. Disconnected the harness and restored to factory set up still no go.
  • I placed the key fob in the cup holder with the car off for the duration of my wash which was about 3-4 hours this afternoon. Was about 50'F nice weather.
  • Inspected the fuses in the panel all looked good.
  • I used damp cloth to wipe down under the hood briefly. It was normal routine I do for car wash all the time.
  • Cleaned and put back cabin filter and air filter.
  • Tried both key fob and replaced both key fob batteries. At one point Low Key fob battery warning was displayed.
  • Disconnected battery (-) terminal and waited an hour. Reconnected, locked then unlocked the car with remote. Get in the car still get Keyless System Malfunction and couldn't start.
  • I have a dashcam plugged into the passenger footwell usb. Been using it this way since new and no issue.
  • Accidentally engaged the ebrake during interior cleaning and left it on.
  • Brake feels super firm but brake light does lit up.
  • Honk doesn't work.
  • Ebrake light was flashing sometimes.
  • Could not open the tail lift gate with like double beep.
  • Sprayed the underside of the car to clean off dirt and salt.
  • Serviced at dealership last month / 1000 miles ago and the battery status on their report was green.

Now about 6 hours later I tried to start it again it won't even crank. And some new weird things like Door button wouldn't work, mirror doesn't fold, remote sometimes work sometimes not. Had to use physical key to lock the car once.

Like I said I'm suspecting the battery is dead. Could it be the ~2 hours i was cleaning the interior and keep having the doors open and close with the key fob in the cup holder cause the dome lights to drain my battery? Or could it be the Fortin Evo-One draining? I don't have a battery tender/charger or multi-meter nor I couldn't try to jump start with the car head in my narrow driveway. My best bet is to take the battery to Autozone for testing. If the battery is indeed dead I will get a Duralast Platinum (or any recommendation?) and see if it will fix it. My last option is tow it to the nearest dealership if changing battery doesn't help.

Could I have damaged the electrical system during my car wash? I've been wash the same way for years with my past BMW and this CX9.

TLDR: Car won't start and throwing dozens of malfunction messages after routine car wash by myself. Suspecting the battery and seeking advice.
I believe your battery is dead. I’ve owned a 2004 Jeep Grand Cherokee, 2007 Ford Explorer, and a 2016 Toyota Highlander and every time my battery was dead, all of the things you mentioned occurred. For example, when my battery died on my Toyota Highlander, I got brake failure codes, AWD malfunction codes, etc. I went to my local AutoZone, replaced the battery, and all the error codes went away.