Alex, I can't express how grateful I am for this fix. It actually worked on my 550D. There are hundreds of reports of this issue on the Internet since like 2009 and here is the solution finally)
The only issue I had was that during ML install SD is still write protected. Install doesn't report any error but it doesn't commit ROM and boot records to the card. So, in order to complete the installation I had to set boot records on SD with hex editor on PC manually.
The only issue I had was that during ML install SD is still write protected. Install doesn't report any error but it doesn't commit ROM and boot records to the card. So, in order to complete the installation I had to set boot records on SD with hex editor on PC manually.