Turn key, 1 click, all power lost

[Stoney938]

Not exactly sure what's happening with my 99 with a 2.5 L engine and manual transmission.
Please keep in mind that electric is my worst subject. A buddy who doesn't know much about cars was borrowing the Jeep and thought the battery was dead because the alternator died. So he replaced the alternator.
I went to start it up after getting the battery charged and turn the key it clicked and died and turning the key back and forward did nothing, as if there was no battery in the Jeep at all. So I disconnected the battery terminals for a minute and reconnected them and slowly turned the key and the Jeep started.
I turned it off to get gas down the street and it wouldn't start.
Turning the key to accessory mode will light up the dash and turn on the radio and everything , but Every time I go to turn the key to start it clicks once and as soon as the starter gets power it clicks and then it loses all power and acts like there's no battery connected at all.
So I have to disconnect the battery for a minute and then reconnect it to get any sort of life back in the Jeep. I was able to get it home by pop starting it and I replaced the ignition switch and the starter but it still has the same issue. Could it be the starter relay? Or is there a short somewhere?

 

[CharlesHS]

Since you have replaced the ignition switch and starter; I would expect they are in good working condition.
Check the battery cable clamps and battery terminals for oxidation; clean, reattach and tighten the clamps.
Check the ground cable on the engine stud near the oil filter, clean, reattach and tighten.
You should also consider measuring continuity (ohms/resistance) of each battery cable while they are disconnected to see if the strands of the cables are corroded.
Verify the voltage on the battery terminals with the cables disconnected; should be 12.4-12.8V.
When you turn the ignition and only get a click; you need to have someone testing the voltage see what the voltage drops to when attempting to crank over the engine. The voltage may drop to 12.1V and then slowly climb once you have stopped trying to crank the engine.
IF the voltage does not return in a short period; a cell in the battery is going bad.

 

[Stoney938]

Since you have replaced the ignition switch and starter; I would expect they are in good working condition.
Check the battery cable clamps and battery terminals for oxidation; clean, reattach and tighten the clamps.
Check the ground cable on the engine stud near the oil filter, clean, reattach and tighten.
You should also consider measuring continuity (ohms/resistance) of each battery cable while they are disconnected to see if the strands of the cables are corroded.
Verify the voltage on the battery terminals with the cables disconnected; should be 12.4-12.8V.
When you turn the ignition and only get a click; you need to have someone testing the voltage see what the voltage drops to when attempting to crank over the engine. The voltage may drop to 12.1V and then slowly climb once you have stopped trying to crank the engine.
IF the voltage does not return in a short period; a cell in the battery is going bad.

One thing I forgot to mention is while I was driving after I pop started it, I was going about 55 and the radio cut out then the check gauges light came on and the battery gauge was as high as it could go. It was sitting there for probably around 8 minutes until it went back to normal. What do you think about that? Could it be a bad battery?

 

[JMT]

Check your connections, clean terminals and clamps. Do everything @CharlesHS said to do first. Then you should have your answer.

 

[Stoney938]

Replaced the battery, jeep starts fine. Thanks for all the help