Downgrade US996 from Oreo to Nougat.

[Boowho]

Please don't ask me WHY I want/need to do this.... It's not productive....

Accomplished the downgrade this afternoon. Every thing went well EXCEPT the device complained about NO SIM CARD INSTALLED after the downgrade even though it could see the SAME sim card before I downgraded.

So, scratched my head for a bit and then went back to Oreo. Found sim card just fine. WTF???

SIM card was in the device thru-out both flashes.....

Boowho???

 

[puppykickr]

I would tty it again without the SIM card.

It does sound weird, though- what happened.

I wonder what would happen if you put another known working (but unfamiliar to the device) SIM in it when it is on 7?

 

[mikedt]

Please don't ask me WHY I want/need to do this.... It's not productive....

Accomplished the downgrade this afternoon. Every thing went well EXCEPT the device complained about NO SIM CARD INSTALLED after the downgrade even though it could see the SAME sim card before I downgraded.

So, scratched my head for a bit and then went back to Oreo. Found sim card just fine. WTF???

SIM card was in the device thru-out both flashes.....

Boowho???

Was the phone's IMEI, MEID, etc. showing as blank, or all 0s, or invalid as well with Nougat? But a NO SIM error is often a baseband problem, which can be caused by flashing the wrong Nougat firmware for the LG V20 variant you've got.

 

[ocnbrze]

^^^^^^this^^^^^^^
where did you get the firmware? are you sure it is the correct one?

 

[Boowho]

The firmware for both version came right off LG's own FW DL site.

On the Nougat version the version can be no later than 10F.

On the OREO version I don't know if ANY version of of the FW is flashable.

Did not check the IMEI , MEID for blank or all 0. I'll continue to investigate.

 

[Boowho]

Well, the saga continues. I went back to Nougat this AM. No sim card missing message. However, screen shows 4G-LTE from Verizon (thru straight talk) but the phone app cannot get connected!! Again, WTF. I think this thing might be under the heading of paranormal.

Also, I cannot get USB debugging enabled under developer options.

And I can't make or receive voice calls but mobile data is OK.

I looked at what the phone app setting is and it says contacts.

It still puts out a "warning" screen at bootup that say the bootloader is unlocked. Second again, WTF???

 

[mikedt]

Well, the saga continues. I went back to Nougat this AM. No sim card missing message. However, screen shows 4G-LTE from Verizon (thru straight talk) but the phone app cannot get connected!! Again, WTF. I think this thing might be under the heading of paranormal.

Also, I cannot get USB debugging enabled under developer options.

And I can't make or receive voice calls but mobile data is OK.

I looked at what the phone app setting is and it says contacts.

It still puts out a "warning" screen at bootup that say the bootloader is unlocked. Second again, WTF???

That still sounds like a problem with the particular Nougat firmware you've loaded, assuming everything was still OK with Oreo.

This site lists 12 different Nougat ROMs for the V20 US996 phone variants, plus a few Oreo ROMs as well. But which is possibly the correct one for your phone, no idea.
https://lg-firmwares.com/lg-us996-firmwares/

Can't help any more than that. I've never had an LG phone, but the symptoms you've described can definitely be caused by a problem firmware.

It can't make phone calls but data is OK, that's very likely VoLTE isn't working, which can be a baseband firmware problem. But check that VoLTE is actually turned ON in the phone Settings.

 

[puppykickr]

Ok, now that all of these other problems have erupted-
can we ask why you needed/wanted to do this in the first place?

 

[Boowho]

From my original post starting this thread:

"Please don't ask me WHY I want/need to do this.... It's not productive...."

 

[mikedt]

From my original post starting this thread:

"Please don't ask me WHY I want/need to do this.... It's not productive...."

OK, in that case I don't think this thread will be any more productive than what's already been discussed, i.e. problems are caused by an incorrect Nougat ROM, that's it.

Perhaps someone else who's had experience with flashing ROMs on the U996 phones maybe able to assist more?

Subject is closed for me.

 

[ocnbrze]

and just to be sure......are you sure you are flashing the correct firmware? it needs to be exact for your model. flashing the wrong firmware can cause issues that you are seeing.

 

[Boowho]

It's all a moot point now. Just swapped the US996 motherboard out and the original H910 MB back in.

That' fixed everything.

Thanks to all who responded with positive suggestions.

Boowho