My alarm went off when I popped the hood with the keys in the ignition of my 93 Lexus ES 300, now the car doesn't start. Do I need to reset something?

I EXPECT THATS THE ANTI THEFT WORKING , CALL A LEXUS TECH

have you checked the fuses under hood as well as in the interior under dash, if all ok the key fob may need new batteries

I think that's the alarm system as well.the most important thing is the alarm system is still working?step out yr car try to use remote key to lock n unlocked,if that's working.i don't worry at all.lock n unlock are alarm system reset itself.should be normal,battery is super low or dead .good luck for u

Whoever replaced the batteryif it wasnt you never reset the computer on the car.

Sounds like you need to reset your alarm kill switch, which should be located near the driverside kick panels. GL.

if it has an alarm hook up the cables so the alarm goes off then deactivate it with the remote. if you dont have the remote then you need to take it to an alarm shop and get a remote programmed for it if they cant they will have to remove the alarm and you will need to get an aftermarket alarm for it but yea it wont start because the alarm was on. when you try to jump a car with an alarm even if you have the keys in the ignition the alarm will go off its a fail safe so noone can jump your car to hotwire it. but just do as i said jump it and disactivate the alarm with remote and it should turn over with ignition......
one thing you can try close all the doors lock the doors.....USE YOUR KEY TO LOCK THE DRIVERS SIDE DOOR AND THEN UNLOCK IT. See if this might reset it.....
Best of luck i hope this will help

try this,after locking/unlocking with key,put key in ignition,turn it on to start/release then, whilst the key is still in,press the alarm button.if i remember right,this should do it....

Unlock the drivers door with the key

make sure all doors, hood and trunk are completely closed. put the key in the driver door lock and lock and onlock the door three times.

Even if the remote is fairly new they can lose their programming you may have to have it re-programed