Status update: Heat pump defrost cycle noise

So I called Taylor Heating about the violent noise when the compressor/condenser unit goes in, and out of defrost mode.
They came out and looked around, and took off the front cover of the air handler, then put the system in service mode to where he can turn on (and lock on) just the heat pump mode. This kid was new to the job, - about 7 months he said. I'm not sure he knew what to look for. He had an amp probe, and was probing around the wire in the air handler unit while the system was running.
Didn't seem like he knew how to use the Amp probe, cause he was just randomly clamping it on just the surface of the wire w/o going all the way around the wires and allowing the jaws of the clamp-on amp meter to close.
I mentioned to him that if you are looking for the current of the main compressor in the condenser unit outside, you won't find it in the air handler unit because there is a separate 240 VAC feed outside fed from a sub-panel in the garage. He didn't say anything.
So he proceeded out to his truck to get his manifold set to measure the pressures. While I was in the house, I heard this HUGE noise reverberate throughout the house and HVAC system. I rushed outside to see what had happened, and the guy was just standing there white as a ghoast. I asked him what had happened, and he said: "I don't know".
Oh no, this is not good.
Got my shoes on, and had to quiz him a few times as to what he did to cause that super loud noise.
He basically said that all he did was to screw on the knurled nut of the red (high pressure side) hose to his manifold gauge set to the Schroeder value stub on the bottom outside corner of the condenser unit. He said that it must have been the Schroeder opening up.
Then he sort of backed away while looking at the gauges dazed and confused. I asked what was wrong, and he said that the high side was reading over 500 PSI, and still climbing!
He said it must have too MUCH Freon in the system (while earlier I told him that I suspect that it might be low on Freon since they didn't add any even though the lines are ~10 feet longer than the pre-charge for ~15 feet of line).
I told him, no, and asked him if he knew how the refrigeration process works (in that the compressor takes in low pressure GAS, makes it a high-pressure "GAS", and that the 'GAS' doesn't get converted to a liquid until it cools down and condenses while going thru the condenser coils. He said he didn't know.
Nice kid, so hard to get mad at him.
At least he was smart enough to 'call for help. He got on the phone and called someone. That "someone" asked him if he had the front cover of the air handler off. He said yes.
With the cover off, no air was moving thru the evaporator coils, and the fan was just blowing room air thru the ducts, and not sucking any air whatsoever thru the cold-air intakes, and evaporator coil.
This caused the evaporator coils to get extremely hot, and subsequently caused the Freon pressure to go sky-high.
He quickly shut the system down, and buttoned up the front of the air handler, let the system cool a bit, and then started it all back up again.
The head pressure was coming down, but still not in the ~240-250 PSI range (at 40 Deg. F) that he was looking for.
At one point, the person on the other end of the phone had him check to see how many floor registers might be closed off.
We went thru the house, and he counted 7 registers that I had closed off (in an attempt to force more heat in the master bedroom which I never successfully did).
He told me to change the filter (which hadn't been done in exactly one year since the unit was installed), and to leave the registers open (which they still are).
At the end, the head pressure came down to an acceptable range for the 40 Deg. F ambient temperature from the charts that is printed on the inside of the service panel of the condenser unit.
In the next few days, it warmed up to ~60 Degrees, and so the heat pump system wasn't really running, and I haven't really heard the violent band/crash/explosion noise when the condenser unit goes in/out of it's defrost mode.
So, did opening up 7 (of the many) floor registers in my house really reduce the higher than allowed compressor head pressure that was suspected of causing the defrost mode reversing valve transition to be so violent sounding ?
A: The jury is still out.
Conclusion (drawn by me), is that the acquisition of a set of refrigeration manifold/gauge set like the service guy had connected to my system is DEFINITELY in order. It's just that that whole 'justifying $400+ price tag' thing.
But only then will I know what the effect (if any) of closing floor registers has on head pressures of a 3-Ton Daikin heat pump w/ R410 refrigerant has on the noise level of the transitions into, and out of the defrost cycle.
Course, then I'd need a good "sound meter" too, since I can't find the nice one that I bought from Radio Shack some 30+ years ago.