Solved! Grayscreen after factory reset(REMOVE TAPE FROM SENSOR)

Another title might be:

Stuck on "choose profile" screen as my controllers are not recognized, after changing the batteries. 

update: it seems like after the last step I did to troubleshoot below where the latest software was updated onto my Meta 3, something changed with the functionality of being able to put tape over the sensor above the lenses, like between the eyebrows. I did this to keep the headset on particularly when I was putting it on and off my elderly parents when I could not cast, to assist them with their experience more quickly. This still works on my other M3 that has not had the newest software update pushed yet. Also, for what it's worth, I have a new pair of really chunky eyeglasses and when I put those on they also blocked the sensor in the same way the tape had, and I got the backlit gray screen. I really hope my rabbit hole helps somebody! meta, I implore you to please leave this post just in case it does. 

& for what it's worth, when I did successfully complete the factory reset, my controllers were automatically recognized without having to pair them again or anything.

original:

Changed the OEM rechargeable batteries on my controllers with another set of OEM rechargeable batteries. No big deal, right? No way this can brick my device. 

Then, tried to log on the headset but got stuck in the screen where you select a profile, as I couldn't use my controllers. (Though I could hard press the meta button and recenter the screen).

I have NO third party accessories.  My battery is in the 90s, excluding the elite strap. 

The app could not connect to the headset so I couldn't wipe the device (factory reset) from here. I did however make sure my phone is on the typical wifi network. My bluetooth is on. Sometimes it shows as a connected bluetooth device on my iPhone, but when it does, there's no circle i button next to Connected where you can then hit "forget device." 

Tried restarting by hitting power button for 30 seconds. I see the logo, then a backlit black screen.

Tried restarting by hitting volume down and power button until the special screen pops up. I tried all of the following sequentially, with plenty of time in between each, which again brought me to the backlit black screen.

• Factory reset
• Power off
• Boot device
• Sideload update
  • Followed your directions to another user with this problem with the original cable to my computer. I selected my device to connect. I get the error message: Connection Failed.  Error claiming interface: Ensure no other tabs are accessing the device and that local ADB isn't connected. If needed, run 'adb kill-server' and 'adb detach' in the terminal and retry connect.
    • Gonna be honest, no idea what this means. I went to the command prompt and entered it and obviously, it's not the right thing.
    • So for s&g I went to the Task Manager and killed the background process called adb.exe (32 bit)
      • So this was right!? I then tried again and I got further in the process tree, and got to Recovery software installation complete. Comically with a "continnue" [sic] button.
      • Update successful.
      • Removed device.
      • Tried to start it up, nogo.
      • Hit the power+volume down to get to choices screen, selected Factory Reset.
      • Backlit black screen.  

I bought an extended warranty on this but I am completely beside myself. What's going on, how do I fix this asap?

Thank you.