Unbrick an RBR40

Hi, hoping someone might be able to help me unbrick an unresponsive Orbi RBR40. It just decided to up and die on me, the second one to do so (the only reason I got another one was I found one very cheap on ebay and I have three satellites, replacing the whole setup with something more reliable is unaffordable for me). Since I can't replace it, and the lack of a mesh system is causing family strife, I thought I'd have a go at unbricking it.

I bought a CP2104 USB serial adapter and pieced together info from a variety of sources. Eventually I was able to get a response via the serial connection in PuTTY, during a 30-30-30 reboot it displayed the following:

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Format: Log Type - Time(microsec) - Message - Optional Info

Log Type: B - Since Boot(Power On Reset), D - Delta, S - Statistic

S - QC_IMAGE_VERSION_STRING=BOOT.BF.3.1.1-00110

S - IMAGE_VARIANT_STRING=DAAAANAZA

S - OEM_IMAGE_VERSION_STRING=CRM

S - Boot Config, 0x00000023

S - Reset status Config, 0x00000000

S - Core 0 Frequency, 0 MHz

B - 261 - PBL, Start

B - 1339 - bootable_media_detect_entry, Start

B - 46373 - bootable_media_detect_success, Start

B - 46387 - elf_loader_entry, Start

B - 51688 - auth_hash_seg_entry, Start

B - 53832 - auth_hash_seg_exit, Start

B - 107837 - elf_segs_hash_verify_entry, Start

B - 221546 - PBL, End

B - 221570 - SBL1, Start

B - 313598 - pm_device_init, Start

D - 9 - pm_device_init, Delta

B - 315103 - boot_flash_init, Start

D - 50752 - boot_flash_init, Delta

B - 370199 - boot_config_data_table_init, Start

D - 8549 - boot_config_data_table_init, Delta - (419 Bytes)

B - 381353 - clock_init, Start

D - 7529 - clock_init, Delta

B - 392321 - CDT version:2,Platform ID:8,Major ID:1,Minor ID:0,Subtype:1

B - 395727 - sbl1_ddr_set_params, Start

B - 400821 - cpr_init, Start

D - 2 - cpr_init, Delta

B - 405203 - Pre_DDR_clock_init, Start

D - 4 - Pre_DDR_clock_init, Delta

D - 13172 - sbl1_ddr_set_params, Delta

B - 418500 - pm_driver_init, Start

D - 2 - pm_driver_init, Delta

B - 489721 - sbl1_wait_for_ddr_training, Start

D - 27 - sbl1_wait_for_ddr_training, Delta

B - 505896 - Image Load, Start

B - 514265 - Boot error ocuured!. Error code: 3039

I haven't been able to find any info on boot error code 3039 to see if it looks like a fixable situation, or whether this device is just totally hosed. (I have not been able to interrupt the boot sequence by pressing keys as when this info comes up, it is over in a flash and I can't press any keys fast enough!)

Any advice gratefully received, I am at the end of my tether with this damn thing 😒