It's fairly hard to brick a phone due to software being at fault.
What do you mean by iso update?
The system firmware on the iDevices use IPSW firmware files and the applications installers on the iPhone use a different format than iso.
The iPhone is supposed to work again when doing a restore.
Have you tried restoring the phone via the iTunes application on the computer while the phone is plugged in via the cable to computer?
If yes then try a DFU mode restore, this is different from restoring an iPhone in restore mode. When a phone is restored in DFU mode it flashes and overwrites the firmware completely on the phone. In most cases it's not required and is overkill compared to recovery mode restore but has a higher success rate.
To boot the phone in DFU mode keep the phone plugged in to a computer via cable while following these steps:
1. Hold the home and power button until the apple logo turns off if it isn't off already.
2. Once the phone switches off immediately hold the power button for 5 seconds then keep holding the power button and start holding the home button for 8-12 seconds.
3. Then stop holding power button and keep holding home button.
4. Phone is in DFU mode if it is detected via iTunes in recovery mode.
5. If it is detected perform a restore via iTunes.