Not displaying after power on

On an HP Pavilion x360, a Caps Lock blink code of 3 long + 5 short usually indicates a memory (RAM) or motherboard issue.

First, power off, unplug the charger, and hold the power button for 15 seconds (hard reset). Next, open the back panel and reseat the RAM—remove it, clean contacts gently, and reinstall it. If there are two sticks, try one at a time. Also disconnect external devices.

If the problem persists, it could be faulty RAM or a system board failure. In that case, test with new RAM or visit an authorized HP service center.