techononymous is correct, those dust bunnies can really clog up to the point where just compressed air alone won't do the trick, the breaking up of these are required to get the majority of these.
However, given that the OP has stated that the notebook was completely disassembled, so I'd take it that being the case here, he'd had picked any out while torn down to the core & carefully wiped the interior that couldn't be blown. There would be no need in doing all of that work & what it entails not to do this while everything is easy to access. This service would be a minimum of $300 at any PC shop due to the ways notebooks are constructed & literally hundreds of configurations to keep up with.
For the OP to do this, I take it that he must have more experience than I when it comes to notebooks, while I may reluctantly do this for myself, would never do it for another again for another person, other than basic cleaning, though would pick the dust bunnies that I can physically see & reach & then blow again with all possible doors/flaps open. Too much work for too little in return for a complete teardown when one has no license, insurance & other necessities that a qualified PC shop has.
Although the freelancer's work may be just as good, if not better than a licensed facility, too many are more concerned with seeing plaques that says 'Microsoft Partner', 'graduate of (xyz) university'. as well as a business license, which means the person (or franchise) has paid out a lot of cash to obtain the latter credential. None of which impresses me in the least, there's just as many unlicensed technicians that has worked successfully for over 20 years as there are licensed ones, out of a spare room in the home, a shop in the backyard, and provides just as good (if not better) work over a slick talking clerk who is actually a salesperson for a half baked 'technician' whom barely passed school or other training. And saves the consumer anywhere between 15 to 40%, mainly due to the lack of unnecessary overhead.
And many freelancers are honest enough to inform the consumer that the job isn't worth the cost of the computer. To test this theory, take a notebook that has an actual value of $50 to a shop (to include Best Buy) & see what they charge to repair it. If worth more than the cost of the computer, am not saying they're totally dishonest, though aren't upfront with the facts. However if they want $400 to repair the computer, that is on the dishonest side, if they don't first inform the owner before repairs are made either face to face or by phone.
So after reading the OP's opening post carefully, have determined that outside of CMOS battery replacement (though he did say the current one was reseated), has covered the basics well. However, these batteries doesn't last forever & normally needs replacement between 5-7 years. Some batteries that appears proprietary are actually common CR2032 batteries wrapped in a shell & has wires to attach to a port. If carefully unwrapped, one can duplicate the same process with electrical tape re-wrapped carefully & securely, and a dose of attention to detail (the contact points) & patience. Snapshots with a digital camera or that of a cellphone can help remember the process by steps. The OEM just wants your $35-45 & $12-20 for two day shipping over a twin pack of the same for $5 at a local Walmart.
In fact, this can also be done with rechargeable phone batteries that uses 'AAA' type, just pay attention to how these are daisy chained.
I can attest to this, have re-wrapped more proprietary CR2032 batteries than I can remember, plus phone batteries of my own. As soon as these in my over 3 year old phone goes, will replace with two pairs of rechargeable AAA batteries.
There is one lesser used battery, though forget which one it is, still begins with 'CR', however have only used these maybe 5-6 times in the last 9 years, mainly on not too old (2008-11) HP computers.