To easily solve this ‘The AC power adapter type cannot be determined’ problem, you will need another original charger with the correct voltage/amperage.
First, try using a new Dell power adapter. If that doesn’t solve the problem, replace the power plug. And in the unlikely event that it’s not the adapter or plug, replace the motherboard.
Why is your ‘AC power adapter type cannot be determined’?
As the error message implies, this means that your computer cannot detect the connected charger. The power connector has 3 pins, 2 are power and ground and the third is a signal line for identifying the power supply as a compatible device (Dell). If the laptop does not receive the signal, the power supply cannot charge the battery, but it can power the laptop. This protects the battery from high currents if the charger power is higher than the manufacturer’s specification. If you ignore this message, system performance will decrease and you will notice that your CPU clock speed has halved.