All electrical is on lights, windows, locks but won't start

Hello,

It sounds like you have a weak battery which will cause the alarm system to trigger itself which makes the security light blink.

Here is a guide to help you get the battery changed out.

https://www.2carpros.com/articles/how-to-replace-a-car-battery

Then if the security light still flashes remove the negative cable and hold it to the positive terminal for 5 minutes this will discharge the capacitors in the system and allow it to reset. This guide should help

https://www.2carpros.com/articles/how-to-reset-a-security-system

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken