If your phone doesn’t boot into download mode and you have a black screen after flashing anything wrong. Here's how you unbrick it; worked for me
- Prepare ODIN with the firmware you want to flash (in my case was Gingerbread 2.3.4) and get it ready to go.
- Remove battery, wait for a bit. Insert battery again.
- Flash a recovery with your specific filesystem (EXT4 or RFS)-(If you have EXT4, download ext4 only, don't get ext4+rfs)
- Enter recovery & Wipe | Format:
- Dalvik Cache
- Have ODIN ready. Connect phone to PC.
- Reboot to Download Mode
Hold Volume down + Power + Home button at the same time.
- At this point Odin should have detected your Galaxy Gio (Yellow rectangle should appear).
- Insert the Stock Rom or Custom Rom.
- Click Start button in Odin and wait about 5 min.
- Reboot and wait
If all goes well it should come back to life.
If not, repeat the steps above ^ (Atleast 2x)
Download ODIN 4.42
Download OPS Only
Download DRIVER Only
Here's a video using a USB Jig to Unbrick
if u brick with rom manager you can use only jtag box.
You can try: One-Click UnBrick by AdamOutler
Detailed procedure using ODIN HERE
==List of Stock Roms for GIO==