Security light is blinking on dashboard, car wont start, but you can take a screwdriver and jump the starter off and it will crank but wont stay running. it's a 95 buick lesabre limited. How do I reset the security system?

does it crank fast and not start
or is the starter motor dead.
if starter is dead, jump cable crank it

https://postimg.org/image/ibv99q2hx/
With key in the crank position, jump the load side of starter cut relay, the load side is that line with arrowhead. If everything is ok, the starter motor should crank. If you try that make sure tranny is in park or neutral and parking brake is set. I'm just trying to see if starter motor will crank the engine? I'm not sure about your security system? Jumping the relay bypasses the security for cranking only. Make sure battery has a full charge and connections all good.
You can always take the starter motor off, lay it on the ground, use jumper cables properly from battery to starter motor. At the least it should kick out the drive gear and spin.

it may be your battery. can you try jump starting it from another battery?

a weak battery may light up the dashboard but fail to give enough power to crank the engine.

can you measure the voltage on your battery when it is cranking?

Check to see if you have spark-pull a plug wire you'll need to have someone cranking it over, take a plug wire place a screw driver into the plug wire boot-hole the screwdriver BY THE HANDLE and hold the shaft of the screwdriver close to the metal surface of the engine (within 1/4 inch)-see if you get a spark arc jumping to the engine-if not, you need to look into replacing the crank sensor or possibly the ignition module-also, switch relays from anything related to ignition or fuel with other relays like from the horn or ABS-

sihelp megnals do not work car will not start with key i jumped starter with screwdriver started right up

sounds like it is the starter or ignition switch. To shade tree test the starter you can jump it out with a screwdriver, this is sort of tricky if you have never done it before. Someone will need to turn the key and then you take the screwdriver and tap the posts on the starter, if will arc the screwdriver., but start the vehicle. You can also pull the starter out and have it tested. The see if it is the ignition switch you will need to trace out the wires and make sure they are all working correctly. Good Luck Tim

Easier to test in the car. Put starter back in the car. First, please try to jump start the car. If it will jump and start, starter is OK. If it will not jump start, go to the starter with a screwdriver. Use the screwdriver to short the big red-wire terminal to the small terminal on the solenoid. Be very careful not to short the big red-wire terminal to anything else, or you will get a big spark. If the battery, starter, and solenoid are good, the car will crank. If it does not crank, try again while jumping the battery to another car. If it cranks, the battery is low or the terminals need to be cleaned and tightened. If you have more questions, please reply.

Could be the cables or the starter. Remove the starter and have it tested.

Bad solenoid i would guess. Not making a connection there. Any basic wiring and ignition switch problems should be alleviated by jumping the starter with a screwdriver. I would check the solenoid and starter brushes

bad conection on starter solonid tray diferent starter or solonoid