my 2021 doing the DEEP sleep mode has more to do with batteries condition vice time
it sat since last monday and then yesterday i got the deep sleep notice in the ford pass app
went over and plugged in the battery charger, batteries were at 64% .

i have not locked or unlocked since that monday afternoon, i have checked in with the ford pass app to make sure it was locked .
i charged them to 100% and all was good till about 3 am..ford pass said its deep sleep again. i need to go and start it, but its in the lower 20s outside so NOPE.
i have no idea what is pulling down the batteries so fast, but if it keeps up its going in for new ones

this might not be of any use.
if they found loose grounds before, you can bet there is a sneaky wire not tightened right. after you wash it, open hood and look at everything and see whats getting wet if anything. water will pass by the cowl and drip on the engine easily
have you used forscan to see what dtcs are set when this event happens? techs don't get paid to "touch" every ground and will only go to what is advised.
during my trailer disconnect events i found the truck set codes that described almost to a T what the problem was, but the IP never did, just trailer a trailer disconnected message, turned out to be a shorted out break away battery.
you may end up, putting a hand on every ground on the entire front end to check continuity .

 

Agree. Today I pulled the third brake light and rear brake light assemblies out. There is no evidence of water intrusion, and the pins are dry and clean inside the connectors. May take a look at the brake light switch itself.

 

Check trailer plug socket. Water might be getting trapped inside.

 

The batteries are in parallel

 

Sorry for bumping an old thread. It does keep similar issues under one topic though.
Did this ever get resolved? I have a very similar issue.
Video is here:
I know I had water in tail light, new light is coming and BLIS module. Connectors are clean at rear. This happens even with everything disconnected. Issues started with the truck just sitting. It ran fine when parked. Batteries changed and terminals cleaned.

 

You can try resetting your alarm. There's a procedure for it, I don't have push button start so not sure what it would be for you.

 

I thought it was the theft system at first. I have tried resetting it according to every method on the internet. The mani issue is the BCM never stays on long enough for anything to complete. My truck is doing exactly like the 2020 truck in the video.(lights flashing, display keeps cycling, nothing on the dash, rapid blinking of the start push button, relay in PDB continuously chattering, fob unresponsive) I have pulled every relay and fuse in the truck and nothing stops it. I have tried to read codes with Forscan and a obd2 reader. No codes or unable to connect.

It is very frustrating because I can't even get the truck to a place where it can be troubleshot.

 

Did you look closely and thoroughly for rodent damage?

 

II have checked for rodent damage and other damage. (with 44 fuse installed)I have determined BCM B+ fuse 51 cycles the main power relay or causes the clicking in the PDB
48 cycles mirror lighting
50 cycles the head lights.

With 44 removed
51 B+ feed cycles relay
48 and 50 installed nothing noticed.

This leads me to believe it is a BCM issue. I definitely have a short of some kind. I can see that on the battery voltage through a multi meter and the clicking relay is another indication.

All other fuses and relays in the passenger kick panel and PDB have no effect. I can disconnect every harness at the rear and nothing changes.

Currently, I have 44 and 51 fuses removed so I can see if battery voltage increases with a charger.

 

I' still hoping OP comes back and gives more info.

Today, I ordered 1 month of ALL DATA so I would have diagrams. Essentially, if I put fuse 51 in the main power relay cycles. I was hoping to find an easy way to jumper main power relay and go directly to fuse 51.
I isolated BLIS power and no change.
I have pulled every fuse on BCM and left out, no change.
i did get Forscan to read everything. I can read the BCM, but I cannot get any DTCs reported. Only errors reading or clearing.

At this point I am thinking maybe the BCM is just bad.

 

You have a 6.7 diesel?

 

Check your battery junction box.

 

Thanks so far, today I proved if I remove the feed from fuse 51 to the BCM with no fuses in the BCM the clicking relay stops in the BJB. Now I am certain it is from the BCM out. Next step is to isolate the connectors from the BCM and see if it stops when a connector is unplugged.

I do have a 6.7 diesel. There is a part of me that says have the BCM changed and see if that fixes it. No fuses in the BCM, B+ power disconnected at the BCM, and the lights still flickering with other sources of power applied would seem to point to the BCM or a connector where all 3 power sources come together.

Thanks for the pdf. Today, when I disconnected B+ power at the BCm that was to prove the BJB is clear and the problem exist from the BCM out.

 

I have isolated it down to a connector leaving the BCM. This is assuming the field side connector is not supplying the connection for a short inside the BCM. Now I am trying to find the connector in ALL Data and determine where it goes.

Hopefully, this helps someone in the future.

 

Don't know if this will help.... but maybe help troubleshoot.