LattePanda(Old) Doesn't boot - just red & blue light turned on

Suddenly my LP didn't boot.
The red and blue lights still turned on,
but monitor showed me a black screen.

I tried hard reset.
I tried using another cable and another power supply.
I tried powering through CN2 connector,
Even though I tried powering through Arduino connector.
I wasn't able to reinstall drivers & os reinstall & flash new bios
Because display didn't turn on.

This is enhanced lattepanda, contains 4GB of ram, 64GB of eMMC.

Mouse was turned on. Just like lp booted fine.

I checked it is not issue of HDMI cable or monitor.

It just showing red light and blue light.
Sometimes red light just blinking.

Please somebody help me...