I was connecting an aftermarket alarm saw a spark now I have no power in the car ...car wont start or go into the start position ...head lights comes on door unlock works but door lock wont work help!!!!!!!! Its a 2017 accord ex I use a tester an no power in the fuse box in the car

 

You have blown a fuse. Start with the fuse boxes under the hood. Good luck.

PS: That's why all Honda instructions dealing with wiring changes always state first, 'Disconnect the battery'.

 

Check the 100 amp main fuse link, when it blows you lose most power including start. Not sure where it is on the Accord but on my S2000 it was underhood, there is only one. It screws into the fuse box held in with two bolts. If blown, remove and replace.