7 beeps upon booting. What did I do wrong?

I was reapplying thermal paste onto my CPU (I did warm the TIM in hot water to be able to squeeze out the TM better, but I doubt it would affect the CPU as I dried the synerge before application). After that was done, I reassembled my laptop and powered it on. 7 beeps. I thought, it must be loose. I did move it. So I make sure the CPU was connected properly. 7 beeps. I did this again to make sure I didn't mess up. 7 beeps.
Booted without a CMOS in case some overclock was in the way. 7 beeps. Most attempts with a power drain.
So... what do I next? Is the CPU really dead?

 

CPU fan plugged in?

 

Yes. I made sure the essentials were plugged in.

 

Dell Laptop Beep Codes, so indeed "CPU failure". Carefully avoided touching the pins? And not too much paste, bubbling over the die and causing a short? Lastly; cpu from other system to test?

 

Cannot test on another laptop.
Right amount of paste and even less than that used.
Was careful when reseating CPU.
I think 5 to 6 attempts were done. I can try reseating it again, but I am doubtful the laptop will boot.

 

After another careful reseating, I got the same 7 beeps. Most likely the CPU is dead. Wasn't expecting this to happen, but oh well.
Hopefully I can get a cheap replacement (read: a downgrade) to make sure it isn't a CPU socket problem. At least the motherboard is fine.

 

Put in another CPU that was tested as functional, 7 beeps again.
Is it possible for a CPU socket to be damaged or non-functional and the motherboard still work? Or is there another issue?

 

Check with a new $0.50 CMOS battery. Might not have held a charge before, but that wouldn't have matter as long as default bios settings allowed you to pass POST. The new/different cpu might prevent that ... it's a big "might", then again, as it's only 50 cents ...

Other than that; if there was an inadvertent short during the process then you're left with checking the fuses on the mb. Again; long shot, but not terribly difficult either and a cheap fix. You did remove the battery before cpu-swap?

 

Battery was never present in CPU slot. And I don't know how to check the fuses.
I also checked without the CMOS battery, and nothing. Don't know if I can get another CMOS battery as I'll be away from the laptop for some time.
Also checked without TIM to see if the TIM was the causer. Same results.
The laptop is meant to be sold. If it doesn't work, it's not a big loss to me as I can sell the parts, but still...

 

I have the AW M17x R4 and have a similar issue after an upgrade of the CPU and GPU. My system came up with no issue and has worked fine for a couple of weeks. After a normal shutdown and later restart I was met with 7 Beeps and the rest you know. Unfortunately my system is out of warranty and has been longer than 90 days which DELL uses as an excuse to not renew it. If anything I have learned from this it is to never allow my warranty to lapse because you will eventually need it particularly with their high end machines. I will try the several reflow methods that I've seen online and get back atcha with an update.

 

It might be good for me to hear about this for my desktop, but other than that, your efforts may not be of use to me (though I hope your problem gets fixed).
I've decided to scrap the laptop and sell the parts. I was originally going to sell the laptop, but because the mobo is damaged, I can't do such a thing anymore. The scrap, though, should come close to what I was going to sell it for, so it's not too bad of a loss. It'll take longer to get the money, though.