I have an 88 240 dl and tonight i was getting to go to the gym turned it on and it was running smoothly i ran into the house and when i came back it died and when i went to re start it everything on the cluster went black and it wouldn't crank over and I don't know where to start. I did replace the battery with a new one back in April. Its been running great with no issies until tonight. Any suggestions would be amazing

 

Start by trying to jump it, obviously something electrical failed, may be something got disconnected...

 

for sure as lev has said try jumping. make sure battery connections clean and tight. if it starts you could also check to see if the alternator is working ok with your voltmeter.
if it fails to start then maybe take the battery to an autozone or similar to have it load tested and go from there.

 

My plan is to look at the battery first and terminals in a few hours cause before that happened it was running well most of the day

 

Do you own a volt meter? even a cheap Harbor Freight multi-meter is worth owning. With that in hand, test the battery voltage with car off. A charged battery will show 12.6V or so. A drained battery will show 12.2V or less. If its way less, like less than 10V may mean you have a dead cell in the battery. Now get a jump start. Give the car a few minutes with the jumpers hooked up to allow the other car to give it a base charge before cranking. After you remove the jumper cables, measure the voltage across the battery terminals with the engine running. It should be in the 14V range (no less than 13.5V). If it shows something in the 12V range, that means your alternator is not charging the battery. After that, check cables to the battery, fuses, wires to the battery, wires to the alterator etc. With the big cables, look for any melted or bubbled insulation, corrosion around the terminals. bubbles mean the cable has internal corrosion which will add resistance and will create heat - leading to hard starting, failures in the insulation and worse.

 

funny thing thos morning i put the key in after moving the battery back an inch and it fired right up so i turned it off checked the cables to the battery they look good the alternator was working fine and the cables to that were tight and normal looking i am going to pull the battery and have it tested and probably warrrantied but it started right up like nothing happened the night before

 

You have a major wire not making good contact intermittently. You need to find it. Check as many connections as you can get to. It may also may be your ignition switch that is failing. Jiggle it when the problem occurs, that may help.