Charge it with the original charger for at least an hour, then hold the power button for a few seconds. If the charger light never changes or it still won't wake up, contact the brand's support.
Most scooters that seem dead have a flat battery, a battery that shut itself off after sitting unused, or a power button that wasn't held long enough. A scooter left completely flat for weeks may not wake up at all and needs checking by the brand. The battery and controller are inside the deck, so never open it.
Step-by-step checklist
Work from the top. Steps go from free and easy to shop jobs. Switch the scooter off before touching any connector. Tick each step as you go. Your progress is saved on this device.
When it's time for a shop: if you've worked through every step and the problem is still there, take the bike to an e-bike shop. Bring your notes on when it happens, plus the code.