Hi,
Do try these troubleshooting steps that may help in fixing that problem.
- Do a hard reset, remove the battery and AC adapter then press and hold the power button for 20 seconds. Plug just the AC adapter first, power it on and see if it gets pass the Sony splash screen and loads to your desktop screen.
- If it still gets stuck on the Sony screen try and load BIOS and see if your HDD is being detected.
- Next is to try and reseat the RAM, remove them for couple of seconds then put it back in and see if it will load your desktop screen normally.
- If that doesn't work do remove the HDD and see if it will get's stuck on the splash screen.
- Lastly, do contact Sony support for a repair if it's still under the factory warranty.