Red flashing light

[Steve g]

Replaced battery. Now I have a small red light left side , bottom of instrument panel on my 99 that. Lights and dash works but won’t crank. Light is flashing

 

[Jerry Bransford]

That sounds like someone installed an aftermarket security system, the TJ's cluster doesn't have a factory installed small red light in that location.

 

[Steve g]

Yes it’s below the cluster in the dash by itself

 

[Jerry Bransford]

Yes it’s below the cluster in the dash by itself

If you're not electrically savvy I'd take it to an alarm installing shop and tell them to disable/remove it.

 

[CharlesHS]

Replaced battery. Now I have a small red light left side , bottom of instrument panel on my 99 that. Lights and dash works but won’t crank. Light is flashing

IF you look below the dash board there is probably a three position switch which is for when a Valet is parking your Jeep.
IF you find the switch; determine which position it is in and one of the other positions should disable the alarm system.
The alarm system I had on my '98 XJ had these functions ....