First of all, sorry for late reply/report, I changed my ISP a few days ago and this LTE service is still (very) unstable
After a few days couldn't go online, I did quite a lot of testing every now and then and here are the results:

Method 4

After unrar Garmin.rar and placed the 2 files namely gupdate.gcd and update.txt in a micro SD, then I unrar the 113201000390.rar and dragged it over the updater.exe, after putting the nuvi in pre-boot mode, I clicked “OK”.
The result I got was

“The Garmin device is unable to program the requested memory region.
This could be due to an incompatibility between this application and the Garmin device.
If this error continues to occur, please contact Garmin Technical Support.

And it didn't generate a file called 'last_id.bin' on the card and there was no a folder called 1131, did I do something wrong?

P/S: This happened in a blink of eyes and gone, however, I managed to print screen after clicking the “OK” button and the box titled “Updating Software In…”
Nuvi 1690 Software Version 2.60
Erasing…
(this may take a few minutes)
On the device, the screen showed “Loader loading”.

I was also trying every now and then different methods, in case I got some luck, who knows, and here are the results:

When I tried with QuickCure
I got the windows showing:

Title: Updater
The Garmin device is not responding. Please ensure the following and try again:
1. The Garmin device’s Interface option is set to Garmin or Host mode.
2. The cable is connected to the correct serial port.
3. The Garmin device is turned on.

P/S: At the beginning of this trial (a few days ago), it processed at first or second click, but yesterday when I tried again with this method, I needed about 30 clicks (this really worried me) before it started to process the update

Title: Updating Software In…
Nuvi 1690 Software Version 2.60
Updating…
100% complete, 0:00 remaining

After that
Update Complete
The update was successful (But nothing happened)

Could you guide me with other methods to flash the device?

Or any ideas/insights to be shared?