HTC One m7 OTA update to Lollipop fails with "red trangle exclamation mark inside a htc one" graphic at recovery

*** TAMPERED ***
*** RELOCKED ***
V7_UL PVT SHIP S-ON RH
HBOOT-1.57.0000
...
OS-5.11.631.8

(bootloader) version: 0.5
(bootloader) version-bootloader: 1.57.0000
(bootloader) version-baseband: 4T.27.3218.14
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main: 5.11.631.8
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) serialno: -
(bootloader) imei: -
(bootloader) meid: 00000000000000
(bootloader) product: m7_ul
(bootloader) platform: HBOOT-8064
(bootloader) modelid: PN0712000
(bootloader) cidnum: ROGER001
(bootloader) battery-status: good
(bootloader) battery-voltage: 4023mV
(bootloader) partition-layout: Generic
(bootloader) security: on
(bootloader) build-mode: SHIP
(bootloader) boot-mode: FASTBOOT
(bootloader) commitno-bootloader: dirty-e47fb74b
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0

I had TWRP and it was rooted but S-ON was kept on. I have since installed XPosed framework and that's it, didn't flash another othe ROM. I have unrooted with SU and flashed a stock recovery recovery_stock_155hboot_htc_one_m7 with flashboot flash recovery.

What shall I do going forward from this point to get Lollipop OTA?

Thanks!