RTROMO1 Boot Loop after update

I have a RTROMO1 that has been running well for years. After the last SW update (01-04-2024) upon reboot the LED’s on router wouldn’t start. After waiting 20min I initially tried 2 led rollback, no success.
Tried to re-flash w/both an xfat & ext4 media kit on a USB key without success.
Upon connecting a USB serial adapter I received the following output:

BootROM - 1.73
Booting from SPI flash

U-Boot SPL 2022.10-rc4-OpenWrt-r16653+119-44ce70f0e2 (Sep 15 2022 - 18:21:35 +0000)
High speed PHY - Version: 2.0
MiniPCIe/mSATA card detection... MiniPCIe
WWAN slot configuration... PCIe+USB2.0
Detected Device ID 6820
board SerDes lanes topology details:
 | Lane # | Speed |  Type       |
 --------------------------------
 |   0    |   5   | PCIe0       |
 |   1    |   5   | USB3 HOST0  |
 |   2    |   5   | PCIe1       |
 |   3    |   5   | USB3 HOST1  |
 |   4    |   5   | PCIe2       |
 |   5    |   0   | SGMII2      |
 --------------------------------
High speed PHY - Ended Successfully
mv_ddr: 14.0.0
DDR3 Training Sequence - Switching XBAR Window to FastPath Window
mv_ddr: completed successfully
Trying to boot from SPI
ERROR: Invalid data checksum in kwbimage
Trying to boot from BOOTROM
Returning to BootROM (return address 0xffff05c4)...
BootROM: Image checksum verification FAILED
BootROM: Bad header at offset D4200000
BootROM: Bad header at offset D4400000
BootROM: Bad header at offset D4600000

BootROM - 1.73
Booting from SPI flash

U-Boot SPL 2022.10-rc4-OpenWrt-r16653+119-44ce70f0e2 (Sep 15 2022 - 18:21:35 +0000)
High speed PHY - Version: 2.0
MiniPCIe/mSATA card detection... MiniPCIe
WWAN slot configuration... PCIe+USB2.0
Detected Device ID 6820
board SerDes lanes topology details:
 | Lane # | Speed |  Type       |
 --------------------------------
 |   0    |   5   | PCIe0       |
 |   1    |   5   | USB3 HOST0  |
 |   2    |   5   | PCIe1       |
 |   3    |   5   | USB3 HOST1  |
 |   4    |   5   | PCIe2       |
 |   5    |   0   | SGMII2      |
 --------------------------------
High speed PHY - Ended Successfully
mv_ddr: 14.0.0
DDR3 Training Sequence - 2nd boot - Skip

At this point I’m slightly out of my depth and could use some advice on unbricking my router. Any guidance would be greatly appreciated.

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