Hi, hope anyone here can help me.

I bought a new phone and left my S3 on my safe thinking it was a great idea to backup my bitcoins in it (stupid idea)
A few days ago i needed to do a BTC transaction and to my surprise the phone was giving the SDS (sudden death syndrome) error which only lets me get to the download mode screen.

I have read a few forums post, but haven't really found a definite way that describes how to re-install the firmware without losing all the data inside. I don't need network connection, my idea is to get in, transfer bitcoins and toss the stupid phone to the garbage.

Phone: GT-I9300 unlocked
Rooted: yes
Firmware: stock

To the working solution I'll send some bitcoin as a thank you.