Hi Everyone:
Thanks to some advice from blue1k, I used the Nokia Care Suite to change the ROM on my unlocked Lumia 1020 which I purchased trom the Microsoftstore.com after reading the article on this site about the pricing. PLEASE NOTE, ANY ADVICE FOLLOWED HERE IS AT YOUR OWN RISK. THIS WORKED FOR ME, BUT IT MAY BRICK YOUR PHONE, OR CAUSE OTHER PROBLEMS, AND MAY VOID YOUR WARRANTY.
The steps were:
1. Download the Nokia Care Suite (can't remember where I found it, but I believe it was a search on this forum).
2. Search on YouTube for a video of using the Nokia Care Suite to flash a Lumia device. Basically, once you've installed it, you run the Data Package Manager and login with blank username and pwd. In there, you enter the product type RM-877, but for the product code, use the Rogers one - 059T1V9, and select search.
3. Once it finds it, download that ROM.
4. Once the download is completely close the Data Package Manager, and Open the Product Support Tool for Store 5. Again sign in using empty username and password.
5. With your phone still disconnected, in the Product Support Tool, select File/Open Product, and then filter to RM-877, then select that, which should say (Lumia 1020), and select 'Open'.
6. On the bottom left, select Programming/Recovery. This will load the ROM you downloaded.Ignore the error.
7. Without plugging in your phone, select Start. This will get you to the Recovery screen, where it will assume your phone is not bootable.
8. Turn your phone off, and then plug it in, and follow the instructions to soft reset the phone in the Recovery screen, and immediately after you feel the phone vibrating for the soft reset, select 'Retry'.
This should start flashing your phone to the Rogers Rom. It will remain network unlocked, but you'll get back your AT&T LTE if you're on AT&T, including Network sharing. Rogers has also formally released Cyan and 8.1, so I've been able to upgrade to those. Phone is working wonderfully now.
Thanks
Tamir