Bingo. I finally succeeded, now I have zero bad blocks and the RB493G is running like before!
What was my critical path to reach the goal:
- Set the “next-server” in DHCP network of my main router (also mikrotik) to ip address of my computer.
- Set the “boot file name” there to “openwrt.elf”.
- Run the Solar Winds TFTP server with the “openwrt.elf” file it its root tftp directory.
- Boot the backup booter with dhcp boot option, elf image downloaded and run smoothly.
- The bad blocks were removed during the openwrt boot up process.
- Made “mtd -n erase /dev/mtd5” and “mtd -n erase /dev/mtd6” with error message that one block was not able to unmark as bad block (but finally there is zero percent of bad blocks…).
- Netinstalled RouterOS.
Everything looks good and works as expected.
License stayed untouched, no “format nand” was performed at all.
I did not need any openwrt running device nor to run any kind of linux anywhere else. Everything was done from one pc with win 7.
Beware: Only single partition is supported, need to repartition to 1 before step 4, if more partitions are created.
Big thanks to Alvaro Antelo.
Really. Thank you very much.