[aman704]

I'm using blackberry 9790. My phone was giving me problems from some days and it had an unofficial OS 7.1 bundle 840.
I decided to downgrade the OS to the official 7.1 which was not out.
I followed the stuff mentioned here http://crackberry.com/how-downgrade-...erating-system
What I skipped was the first step since I had new windows installed in my computer so previous versions weren't installed. All went fine until I wiped the device. It shows the error 507 and I could not proceed as it was mentioned in the link.
My apploader is stuck on this screen:

and DM shows this screen:

I have already installed the Official os which I downloaded in my computer. I had also deleted the vendor.xml file.

Please help me! My device does not work anymore

[OniBerry]

Error 507 means you have to reload your OS on the device, as it is no longer there.

KB02792-BlackBerry smartphone displays Error message “507” when upgrading BlackBerry Device Software

[aman704]

Which OS should I try?
Nothing really happens when I install the lower edition of the official OR.

[DWPGQ]

The next OS is always the best option..........the fact that you had problems with your last OS could mean that it was just a bad install.

[zocster]

Aman,

Remove all OS from pc, using add remove program.

Delete all the os folders in shared directory

Delete apploader folder

Reboot PC

Heard 7.1.0.523 is out for a few carriers, so install that.

Google vendelete and run it

Run loader.exe

[g000se]

Awesome advice - i consider myself to be BB savvy but this was doing my nut!!

Thanks for the clear concise instructions