Neo, I understand what you suggested but like I stated above, if one is not able to get a good mtd3 dump from the start, how would one go with the repair mtd3 option? It asks for a good mtd3 file, right?
If you have a suitable/good env file, you could try using any MTD3 file of the correct size, but the config might not be correct. Once you 'repaired' the MTD3, you could then reset the router to defaults - that should load the default config over a potentially messed up one
But generally, the idea is to back up the MTD3 with the RRT before you need to use it to repair the router
Also, I was of the view that one can run the defragenv command on the bootloader without a serial console as well using PCTool.
Well, I tried to use the command in the RRT via the bootloader connection but it didn't appear to be supported. If you know any different, please post details
In any case, the RRT does the same job, so it shouldn't be much of a problem.
But I have been messing around with the tool since then and it has yet to give me an error. I'll see if I can manage to get a good copy of a DSL2640T mtd3 and try the repair using this tool. I will post my results.
If you can't find a good mtd3 file, then I could try modifying the RRT to create a dummy mtd3 file that would do the job (the router would need to be reset to defaults as explained above).