How to recover my new Thingy91?

[ReggieMax]

After unpacking I followed the first step at nordicsemi.com/thingy91, which is to update the firmware. I followed the linked instructions to update the modem and application via USB using freshly-downloaded desktop nRF Connect v3.3.3 tools and the files from the latest package (modem: mfwnrf9160120, application: ...\Thingy91\thingy91_fw_2020-04-29_bc7ade8b\images_full\thingy91_ltem_2020-04-29_bc7ade8b.hex) as recommended in a month-old thread "No connection to network after update - No LED indication"
I have the same result/problem as the original poster in that thread, but the responses there have not helped and I have not gotten any responses to my follow up question.

The first sign of trouble is that the modem fw update instructions state at the end of that page that AT+CGMR can be used to check the update. However, when using nRF Connect v3.3.3 - LTE Link Monitor all AT commands time out (again, my screen looks the same as the OP's in that thread).

The second sign of trouble is that I can find no clarity on which application file should be loaded to provide the same functionality as out of the box, or at least allow me to proceed with the Getting Started instructions for registering my device and connecting to the nRF cloud. (The contents.txt file does not answer this question.)

What should be my next attempt?

[ReggieMax]

Thank you! As I described in my post I have already tried your exact instructions. Today I tried it again with v 3.4.0 of the nRF Connect App (still using USB) I still get the same results: no flashing LED and no response to AT commands.

Note that at the bottom of the Programming Modem Firmware instructions it states "If you want to verify that the update was successful, check the version of the modem firmware by running the AT command AT+CGMR (for example, in LTE Link Monitor)." This step does not work - also as reported before.

Also note that the Programming Application instructions are not clear about whether SW3 or SW2 should be pressed during power-up in order to load the images_full/thingy91_ltem_2020-04-29_bc7ade8b.hex application. I have been using SW3 as described in the other post that I referenced. (I have also tried the debug version.)

So what to try next?

[Martin Lesund]

Hi Reggie,
What does the output log from the Programming app say after you have put the device in MCUboot mode (press inn the button on Thingy:91 when you turn on the device) and then try to flash the "thingy91_ltem_dfu_2020-04-29_bc7ade8b.hex"?
(please share the log or screenshot) 

Do you have a nRF9160DK as well so you could utilize the "debug out" with a 10-pin connector and flash via that? 
(or another external debugger)

[ReggieMax]

I do not have a DK. According to the literature it is not required. I do have a 90's vintage JTAG programmer :-)

[Martin Lesund]

Hi Reggie,
You are not using the correct .hex file.

Please use the DFU file as I have mentioned in my two responses: thingy91_ltem_dfu_2020-04-29_bc7ade8b.hex

Found in: [images_dfu_hex/thingy91_ltem_dfu_2020-04-29_bc7ade8b.hex] 

[ReggieMax]

That does work much better - thank you. The online instructions had led me to believe that only files from the "...images_full..."  directory should be used. But now I see that maybe that applies only when using the debug probe. Probably a case of PEBCAK.