second time amp has died why?

what is going on here? i had a ZX1500.1 for 5 and a half years with zero issues on stock electric between 3 different vehicles. My ZX2500.1 died earlier this year after only about 4 months of use, i sent it off to kicker for repair and got it back, not long after i lost my sub and had to buy a new one. this amp as is has been used less than a month and a half. Sub is a Fi SP4 18@1.84 ohm load i was bumping at close to max volume day before yesterday, i arrive at my destination with time to spare so i sit in the truck with the engine off for about 45 min doing paper work with the stereo on at 1/4 volume. i had to run into the store so i shut off the truck accessories and go in, i come back out and turn the radio on again but no sub. i think the sub may have died or a cable came loose. so today i pull the amp and bring it in. the power light comes on, the protect light stays off. no signal output is produced what so ever. i have not opened it yet to check it out but it has got to be the amp at this point. zero bass boost on amp, zero deck EQ, loudness, or bass boost. gains at 1/2 up on amp with remote bass volume knobb in use. the remote volume knob is used at 1/3-1/2 level. the truck has zero gauge power/ground, a 280A mech man, and 4 group 31 batteries. 250A fuse on kicker did not blow, sub and amp were never more than warm to the touch. lowest voltage the amp ever saw was 12.2 while engine off and 13.6-14.2 while running. im about to pull it apart but wth am i missing here? should i just go buy a squared audio amp and be done with it? im at my whits end with this system and its failures. edit: just pulled it apart and i have one resistor and a mosfet up in smoke (from what i can tell). someone please give me data on these parts, the resistor im sure i can find but where can i buy a mosfet? i want to solder this tomorrow and fix it rather than shipping it out. secondly; WHY IS THIS HAPPENING?!?!?! what do i have FU**ED up that is causing this 2500 to blow up?ZX2500.1 - SP4 18"

Eclipse 34320 - dual 10" mids

Audiobahn A275HC - tweets

KX3 xover

P7800HD deck

knukonceptz wire

custom 3/8" copper plate ANL fuse

4 group 31 1150CCA batteries

That Kicker amp spec say is stable to 2ohm. Your speaker is below that. Think of it like,kind of this; a jumper wire from (+) to (-) on the speaker output would be a like a 0ohm speaker, and would short the amp. The specs say your speaker is 1.27ohms. I have a 1200 Watt Pyle Clipper Series amp, and it goes right into overload with anything under a 2ohm load on the first bass hit. Your amp has the protection, so don't know why it keeps frying. I would try a higher ohm speaker to see if it lasts longer. The specs for that speaker show DUAL1 = .65 ohms and DUAL2 = 1.27ohms. Try 1 gauge power, and 0 gauge ground. There are 1ohm stable mono-block amplifiers, that would suit that speaker better.

why would you want 1ga power and 0 ground?

the subs coil is .65 ohm so when wired in series it will be 1.3 at the coil. however after rise from the solder, wires, and terminals will raise it. in this case to 1.84ohm. as for getting a higher ohm speaker one could splice in a larger wire in the middle to raise the impedance a bit but im not sure if thats necessary. 99% of the time the amp would not be running anywhere near 2ohm anyway but would be more like 3-26 ohm or more depending on frequency. im not sure how running a different power and ground wire would fix anything. ZX2500.1 - SP4 18"

Eclipse 34320 - dual 10" mids

Audiobahn A275HC - tweets

KX3 xover

P7800HD deck

knukonceptz wire

custom 3/8" copper plate ANL fuse

4 group 31 1150CCA batteries

amps die for a lot of reasons. you are already a bit low on the ohm load and keep in mind that the resting ohm load is not what you get when the music is playing. the ohm load can get lower than that depending on the audio frequency. so certain songs can tax your amp a lot harder than others. the other common reason for a dead amp is a bad connection or maybe just not the best connection. if your connection is a little too much resistance back to the battery, then it might work just fine for normal listening but once you start to max it out it just becomes too much work for the amp to pass that much current through those connections, and it causes the components to fail. the connection itself could be perfect but it might need to be moved to a better spot. long story short, when you are playing with that much power, everything has to be nearly perfect for you to not have these kinds of problems. to check your ground, put a lead of your meter to your ground spot and touch the other end to your negative battery terminal of the closest battery, there should be almost no resistance, less than an ohm at least.

I was always told, to use a thicker ground wire, than power. I do this on my cars too, and never have problems. Most of the audio install guides I read, say to use a thicker gauge wire for ground than the power wire. A resistive ground is not safe either. Grounding right to the battery is not always the best way. A nice solid ground post on the chassis is great. Also, ground everything to the SAME POST. Using multiple grounds is what gets you a ground loop.

well, i can understand the larger ground concept, but why would you recommend using 1g power wire if he already has 0g? an amp with that much wattage needs a 0g power and ground at least. now you could go bigger on the ground and it wouldnt hurt but at some point it also doesnt help, its just wasted because the ground will never have to pass more current than the power wire, so as long as the power wire is big enough then the same size ground is more than enough.

x2. Whilst +12V voltage drops may be acceptable, GND voltage drops can cause noise, and damage (especially if GND is lost). Hence heavier grounds are recommended - maybe in conjunction with redundant paths to guard against loss of GND.