Before performing a hard reset on your iMate SP3i, be sure to start with your phone powered off first and then follow the steps below.

1. Press and hold soft1 and soft2 keys.
2. Press and hold power button for around 1 to 1.5 seconds. Release power button. Keep hold soft1 and soft2 keys.
3. Later, screen shoould show instructions to ask user to press ‘0’ key to reset to factory default.
4. Press ‘0’ within the timeout period, which is only several seconds only.
5. If no instruction is shown on the screen, repeat steps 1 to 4.
The timing is sensitive.

It’s too bad the iMate SP3i manual has no instructions on hard resetting your phone.