AC750 EX3700 power light blinking green

> [...] the power light was blinking green [...]

   You may be a candidate for the TFTP recovery scheme.  See, for
example:

      https://community.netgear.com/t5/x/x/m-p/1622096#M102004

   Those articles tend to be appropriate for a router whose default IP
address is "192.168.1.1".  For an extender, whose mostly-dead default IP
address might be different, you might need to send the file to an
address like, say, "192.168.1.250", instead.  ("192.168.1.10", and so
on, should still be good for the computer.)

   Also:

      https://community.netgear.com/t5/x/bd-p/home-wifi-range-extenders