A solid white light on the Surface Connect charger usually means the charger is receiving power and is properly connected to the laptop. Since you've already tried a new charger, the problem is more likely with the laptop itself than the power adapter.
Disconnect everything (USB devices, external monitor, SD card, etc.), leave only the charger connected, then:
Hold the Power button for 30 seconds.
Release it.
Wait 10 seconds.
Press the Power button once.
If there is no logo, no fan, no keyboard backlight, and no response whatsoever, despite the charger LED staying white, the issue is likely an internal hardware fault that will require repair. The most likely causes are an internal power issue, battery failure, or motherboard failure.