Obviously this voids your warranty. Don't do this unless you're comfortable working with electronics. I'm not responsible if you choose to do this and you end up breaking your life preserving/saving machine. I had a an extra machine to work on this.
Why?
My Airsense 10 is located on a lower shelf of my nightstand for sound isolation. I use Smartstart to start it, but it's always been a little difficult to reach to turn off. I recently had shoulder surgery and it became impossible to reach to turn off (1). So I decided to dig into it.
I wanted a wired (or wireless) remote to start and stop the machine, but without disabling the existing on/off capability. I installed the switch on my nightstand within easy reach.
I'm not the first to take this approach, I found this thread from 2008 with user feeling_better having reported he/she had done it as well.
How
I disassembled my Airsense 10, identified the terminals used for the start/stop button, and soldered leads to the two pins and brought the wires outside the machine [pictures below and credit to GrantsReviews on Youtube for guidance on disassembly guidance]. This isn't super hard, but there is clearly a risk of damaging your machine...be extremely patient.
Pictures
Removal of the circuit board, with the start/stop switch circled. Unfortunately the terminals we need to pick up are on the back of this.

Beyond what Grant does, you have to remove the large knob and plastic section with the home button on it to get at the back/bottom of the start/stop switch and find the terminals.
Terminals are here, with my two 20ga leads soldered to them (sorry for blurry image - they are the top two terminals in this orientation)

Reassembling the plastic section and how I ran my wires. They are pinched but not badly - should be fine.


Run wires out the to the back of the machine, and drill a small hole to bring them out (strain relief on order).

Once you get here (the unit is reassembled and the wires are coming out the back) you can test it...plug in your power, put on a mask, and short the two leads together which should trigger the start/stop button action.
Wired vs Wireless
With the leads coming out the back, you can now proceed with a switch (wired or wireless)
Wired is easier; less complexity. You need to connect a momentary switch to the two wires which will represent pushing the start/stop button. There are a million choices, I landed with this https://www.amazon.com/dp/B0BZ886132?ps ... ct_details ($10 as of this writing December 2023).
Connect the two leads out of the machine to the two leads of the switch. Use wire nuts, or low voltage connectors (i.e. RC car type connectors - Futaba or the like). And you're done! The switch should now represent the original Start/Stop button, and the original button should continue to work as well.
Wireless is more complex but potentially more flexible. There are likely many solutions to enable a wireless switch to those leads. I use Insteon (a home automation technology). So I ran those leads to an Insteon I/O Linc and connected those two leads to the Common and N/O (normally open) terminals. Then paired a wireless remote to the Insteon I/O Linc, and voila! Wireless start/stop capability.
Honestly, I'm probably just going to use the wired switch...much less complex and chance of things going wrong.
(1) I did get an inexpensive remote controlled outlet immediately following my surgery that toggles the outlet power for the CPAP; but this had 2 drawbacks: 1) the SD card got corrupted after a while, I suspect because it was cutting the power at least 1x / night (obviously not confirmed, but correlated, had never had a problem before). 2) the cool off mode of the machine won't run if I cut the power.