From fit-PC wiki
1. fitlet BIOS reset:
- Power down the PC and unplug the power cable.
- Open the bottom cover (by unscrewing 4 bolts) and remove it.
- Reset the BIOS by pressing low profile push button (SW3) for 3 seconds located near the high mini PCIe slot, as shown in the picture below.
- Plug the power and power up the PC (either auto-on or pressing power button).
- Note: fitlet disassembly video
2. Check the RAM memory:
- Remove the top cover (refer to fitlet Owner’s Manual)
- Verify RAM module is installed and in place. The system will not boot without memory.
- fitlet should be used with low power (1.35V) memory only.
- Install the memory back.
3. Power up without storage:
- Try to enter the BIOS by clicking Del during boot
4. Power supply:
- Verify the power supply is not damaged and functions properly.
- If you have another power supply use it to eliminate and determine the failing side.
- In case you use other power supply make sure it provides uninterrupted power and stable grounding.