@Fivepointfive 

Factory default the extender by holding the reset pinhole for a couple of seconds once the extender comes back up, take it to a completely different location. If it does not, move it to where you had the extender originally, just power it on and leave it. If not, set it back up with the router. If it reboots soon after connecting to the router there may be some incompatibility. If the extender keeps rebooting no matter what you do with it, it may have be malfunctioned.