Default [Q] open .backup from stock recovery

Hello everyone,

I had to factory reset my cinko slim android phone given that it didn't boot anymore (it was stuck at the opening logo). The recovery mode was the only thing available (I use a stock rom).

I had all my phone contacts stored in the internal memory so before doing that I made a backup to my sd card using the stock recovery (it made a 1gb .backup file in my sd card).

After wiping all the datas, I was able to use my phone without any problem but the recovery mode wasn't available anymore (the device gets stuck on the android logo when trying to access it).

So I tried to load the .backup file into another android device from its respective recovery mode but a message appeared reading ''checksum compare fails''.

Is there a way I can access all my datas from this .backup file and get back my phone contacts?

Thank you very much for your help