How can I stop my power light flashing?

@bettychow you need to let us know if it is blinking fast or slow. Fast blinking is usually caused by a battery that is below 20% while a slow blinking light means it is in sleep mode. For that try resetting your Lenovo by unplugging it from the power source, removing the battery (if possible), and then holding the power button for 30 seconds. Any of these can also be indicative off a hardware problem, like a bad battery.

To work on your Lenovo, download the service manual from here It will at ;least help you to work on it. I would start with replacing the battery and checking the DC in jack as well as the power lines to the charging circuit.