1:Only plug in one machine alone, can one be turned on?
2:Check if the adapter is working properly. Replace with another 12V DC adapter, does the machine light up?
If you use mars 3 and saturn series 24V adapters, it will directly cause damage to the motherboards.
If the adapter has a port with no output, the adapter is invalid.
If both ports of the adapter have 12V dual output, the motherboard is damaged. If you connect the motherboard of a machine separately, can one of them be turned on normally by long pressing?
If the machine cannot be turned on normally, the main board is damaged.