1) Bricked device MODEL, Firmware version, HWID.

Garmin DriveSmart 50 LMT-D unit is s/n 4ff020111 made in Taiwan .
I think the internal pcb is s/n 01A01Q368L22202,
Firmware ver unknown,
HWID not known and not accessible via USB and pre-boot.

2) Why and how the device got bricked.

My non electronic minded friend was trying to update his maps and software to latest. It bricked on him during that process.
He is not sure exactly at which stage as updates take a long time.

3) Symptoms: what's wrong in your device?

Wont boot

4) Does your pc see your device ?

No, it sees a small activity during 'system' stage

5) List all the procedures you already tried to unbrick it and their results and errors messages obtained.

I am an electronics eng and try to fix many electronic devices as hobby. Thus, I got given the device to ry fix it
5.1) Replaced dead 3 wired 3.7V Li-ion battery new as old one gave an on-screen battery problem icon and would not charge up:
The battery would not charge w charging problem on screen. I checked the battery, tried freezing and heating methods reviving it etc but was dead.
Rather than try replacing battery’s internal safety pcb I replaced w new battery.
Then device battery issue went away.
5.2) But still with power on only the 'Garmin' name appears.
Device boots no further.
'G7ToWin64' program configured for usb does not connect.
I think this device is too old for warranty cover.

5.3) My laptop does not recognize it via usb.
My laptop recognizes my own Garmin Nuvi 750 via same usb cable and port ok, ie the cable and usb laptop hardware, driver etc are ok. Driver is latest.

5.4) Powering on and pressing above the G for Garmin I do get into 'system' and then 'loading' modes.
But nothing loads.
The device eventually powers off.
When the device is in 'system' mode i notice my Win 10 laptop bleeps to say it did recognize some usb port activity however it never registers as a connection
on the laptop 'device manager' usb ports list.

5.5) No SD card is installed or existed for this device.

5.6) I cleaned USB receptacle with alcohol and soft toothbrush. There is no debris inside the usb receptacle. It looks ok under microscope.

6) Do you have Garmin USB Drivers installed ? Garmin: USB Drivers Updates & Downloads

I have latest drivers and know they work for Garmin Nuvi 750 as I just now also updated its maps via mapinstall and GarminExpress. re above explanation

7) If you don't know HWID get it by Use program G7ToWin to retrieve your HWID

I don’t know it
I cannot get it as Pre-Boot does not complete and usb port is not recognized on win10 laptop.

I would be looking for structure such as
"<PartNumber>006-Bxxxx-00</PartNumber>
The 4 numerals following '006-B' represented above by 'xxxx' show your unit's HWID."

Written on the box ix 010-01539-2A and barcode 5375915727. Another box label has 4FF020111 barcode
Also Written on a label inside the device attached to back of the display is GP Z050NA -05E GZD050NA5010S
The internal pcb has a label with identifier 15392A 3935372329b 28721G
Written etched on the pcb it says GARMIN 105-02872-00 Ver 6

8) Write down if you already read or tried GarminCure3 tool - the new way to create cure firmware for Garmin devices
How to unbrick a nüvi - step by step guide

Yes I read it .
My understanding is I need to have a successful Pre-Boot and I don’t !!!
My guess is there is some sort of flash/prom/ram which has a bootstrap , accessed via the 'loader' which has gone bad/inaccessible.
Of course, some hardware failure might have happened too . But I checked the pcb under a microscope and could not find any bad joints, smells,
hot components, damaged looking components etc . I did clean the pcb a little as there were a few small solder splashes. But this did not help.
I also tried remove and re seat the screen/digitizer ribbon cable, but this did not help.

9) Can you reach preboot mode? If no ,have you followed this? Garmin devices preboot mode

Yes.
It does not complete

10) Probably no , but do you have NV backup?

Sorry NO

11) Once you get a reply and a procedure to follow from our experts, please give an accurate reply about what you did and obtained results.

I am a worldwide electronic and software tech SupportLine eng so understand the value of this feedback
If the onboard loader is corrupt i wonder is there any way to load it via some software bootstrap on an sd card ?
or any other advice other than give up the chase and buy a replacement device.