Is it just stuck blinking at the VAIO splash screen? Do try some of these troubleshooting steps that may help.
- 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 then boot it back up and see if it would get pass the VAIO screen.
- Next to try is to reset BIOS to default, see if you can load BIOS by usually pressing F2. Once in BIOS press F9. If it doesn't load BIOS just take the CMOS battery out for couple of seconds then just put it back in (the laptop should be off when you do this)
- Also try if you can reseat the RAM, take them off and put them back in.
- Lastly, take the HDD out then power it on and see if the laptop will get pass the VAIO screen and if it does you have your suspect but if it won't it's the motherboard.
- Contact Sony Support if it's still under the factory warranty for a repair.