The problem is its not Just firmware... for most users, and me all the other stuff is written in the nand too. By that I mean anything in /var or any other part of the filesystem which gets mapped to MD0.
Ideally users should either install multiboot (from what i've read about it) thereby using the onboard as only a starter and anything that get changed gets changed on your second image on a USB flash stick (and therefore replaceable device).
Or map commonly used dirs to a USB stick so mount /var to a usb stick or something via fstab on the box.
Storing stuff that changes on the nand seems a bad idea but if you have no external storage setup there is no other place, so I understand why vu (and every other STB) use a partition on the nand to preserve stuff between reboots.
Perhaps I just got a bad nand with very few spare blocks and it was down to that. Who knows
I have bought a new box (solo) again genuine, even though I know clones are cheaper. I'd just love to recover this box, bought a hot air rework, bought the Cypress board, but to no avail.
As for a bootloader, I'm pretty sure its all in the nand, I did have 2 full dumps, one that was partially overwritten (this from the original nand on the box that crapped out mid flash), and one from another uno thats also genuine that belongs to a friend.
Programing either didnt work, both programmed to a virgin chip allow the box to boot (which is good), and the box accepts and programs an image from USB but the box does not fully boot. I'm missing "something", and the guys in the official forums are being tight lipped about what. The assumption that the chip is the issue in that its not 100% compatible is all mine, but it seems a reasonable idea because I found a link of another guy who used the E part in his D based project and had issues, it wasn't a drop in replacement as hoped.
Shame there isnt a drop in TSOP 48 thats available to purchase, or some device that can be purchased to salvage out the flash ic and fixing the box.
If you're curious, this is the serial output with the new nand installed with after flashing via USB a image from the usual places (vix/etc).
Copyright (C) Broadcom Corporation.
writing vfd
New NAND flash at 18000000 offset 00000000 size 116736KB
New NAND flash at 18000000 offset 07200000 size 4096KB
New NAND flash at 18000000 offset 07600000 size 4096KB
New NAND flash at 18000000 offset 07A00000 size 2048KB
New NAND flash at 18000000 offset 07C00000 size 1024KB
New NAND flash at 18000000 offset 07D00000 size 512KB
New NAND flash at 18000000 offset 07D80000 size 512KB
New NAND flash at 18000000 offset 07E00000 size 1024KB
New NAND flash at 18000000 offset 07F00000 size 1024KB
DDR Freq: 396MHz
CPU speed: 405MHz
Memory Config: 64-bit UMA
Device Tech: 1Gb
Total memory: 512MB
Boot Device: NAND
Total flash: 128MB
Initializing USB.
Initialize First USB Controller
USB OHCI start : Power Switching Mode Changed from 2000902 to 2000b02
USB: Locating Class 09 Vendor 0000 Product 0000: USB Hub
Try to Initialize Second USB Controller
Initialize Second USB Controller
USB OHCI start : Power Switching Mode Changed from 2000902 to 2000b02
USB: Locating Class 09 Vendor 0000 Product 0000: USB Hub
CFE initialized.
checking usb
ACK :
writing vfd
Starting splash screen.
nand_erase_block 0x1fb20000 0x20000 doneLoader:elf Filesys:raw Dev:flash0.kernel File: Options:mem=48M mem=256M@0x20000000 rootfstype=jffs2 root=/dev/mtdblock0 rw
Loading: !!!!! UNC read error occurred, while reading from NAND flash
nand_erase_block 0x1f200000 0x20000 doneFailed.
Could not load : I/O error