I get you're a farm and you're probably not going to get certified but you should atleast get someone with some crane experience/knowledge that can give you a little bit of guidance and some do's and don'ts because there are a lot of don'ts and if you f around you might find out.
Now that that's out of the way, when a lmi(PAT) is in a lockout/alarm condition it typically locks out function that will decrease the cranes capacity or make the situation worse. So when its locked out you can boom up but not boom down, cable down but not cable up, retract the boom but not extend the boom. It can go into alarm for being overloaded but there are some other situations that can lock you out.
Most common other lockout situation is you're anti two block (a2b) is in alarm which is the metal weight hanging off a chain on the tip of your boom that the cable runs through. If the weight isn't hanging free it activates a switch that puts the lmi in lockout this is to prevent the headache ball from being pulled up into the boom.
With the crane on and in alarm you should be able to look at the bottom left corner of the PAT just above the bypass key. There are two white circles one has stop crossed out and the other has a hook crossed out. The stop circle lit up means you're overloaded or out of your chart and the hook circle lit up means your a2b switch is activated. Typically turning and holding the bypass key one way bypasses an overload and turning and holding the key the other way bypasses the a2b switch. There are certain times when a crane is being set up that the bypass key has to be used but being that you're still learning the crane be careful how you use it as you may actually be in a dangerous condition the PAT is trying to prevent you from doing.
The other thing I see in your picture of the crane is that you have two a2b switches. One has the chain and weight hanging on the main line but the a2b switch for the aux. line isnt hooked up and has a a2b switch bypass, which is the red hard plastic flag on the a2b switch on the end of the boom, with it installed the switch doesn't work. It's installed if you're not using the aux line. But if its removed without attaching the chain and weight the switch will be activated and it goes into lockout. I don't have that specific PAT lmi so this is just some basic stuff, maybe too basic and you know all these things but it might give you a few things to check.