Just to confirm. The box in the picture is a Mecool M8S Pro+. It is not a Mecool M8S Pro L.
My fault 
Do they come with Android rooted ? If it so the method I propose should work. I have a H96 S905 which I made it boot to SD that way also. I think the "Reboot on LibreElec" Android app use that idea.
Sure.
Here is a picture of the location of the reset button on the Mecool M8S Pro+. Sorry about the quality. The phone camera sucks.
A toothpick will fit if you remove the first grill post to the right of the power light. The reset button is at the top of the opening you create. You can also poke around without removing the post, but with something slimmer than a toothpick. I found this awkward and difficult without the grill post removed.
Not all Mecool M8S Pro+ L have that button.
Mine doesn't so I just rebooted it in Android using ADB or inside Android since it is rooted already:
Install Termux in Android, open it and then
su
reboot updateThis will reboot it from SD
Tested your new 8.2.4.1 release with 3 S912 boxes.
- Beelink GT1: Clicks and pops on audio over HDMI. With PCM or passthrough (DTS codec)
- Meecool M8S Pro L: Clicks and pops on audio over HDMI. With PCM or passthrough (DTS codec)
- H96 Pro +: Audio OK. With PCM or passthrough (DTS codec)
This is on a LG B7 Oled TV 4K.
On a older Samsung on 1080p audio works fine on the 3 boxes
On the old 8.2.4-Subtitles-ff (8.2.3 with your Subs patch9 audio works fine on the LG 4K and Samsung 1080p
So this is puzzling don´t know to blame HDMI changes or Audio Decoding changes, don´t know where to start bisecting this.
I have noted that u-boot kernel cmdline are a bit different on these boxes, seems that these are modified somehow by the crappy Android that these boxes runs I haven´t able to find where do these parameters are stored on these boxes.... I have a lot of ARM toys and most of these are in /dev/mmcblkX or /dev/mmcblkXboot0 and the I play with them with fw_setenv inside Linux (uboot-tools). Anyway seems that Android touches boot video mode.
Thanks for your work if I can help with something to fix this just shoot logs don´t show much except that CEC does not work on the LG but the Samsung 
Ok,
I worked around it. Found that killing and restarting bluetoothd put my BT periphericals on working order, so I added a little autostart.sh
(
sleep 2;
pkill bluetoothd;
sleep 2;
/usr/lib/bluetooth/bluetoothd
) &Hi,
New here
Tried 8.2.4-Subtitles-ff and it did fix subs stutter for me on my GT1 Ultimate but it broke Bluetooth Remote.
I have a PS3 remote which was working fine on 8.2.2.3 and now it doesn't pair anymore. Tried pairing via terminal using bluetoothctl and the same happens I enable trust and it does connect but when bluez has to attach the HID device I got an org.bluez.Error.Failed. I do have a cheap BT gamepad and the same happens 
[CHG] Device 00:06:F5:9A:XX:XX Name: BD Remote Control
[CHG] Device 00:06:F5:9A:XX:XX Alias: BD Remote Control
[bluetooth]# trust 00:06:F5:9A:XX:XX
[CHG] Device 00:06:F5:9A:XX:XX Trusted: yes
Changing 00:06:F5:9A:XX:XX trust succeeded
[bluetooth]# connect 00:06:F5:9A:XX:XX
Attempting to connect to 00:06:F5:9A:XX:XX
[CHG] Device 00:06:F5:9A:XX:XX Connected: yes
[CHG] Device 00:06:F5:9A:XX:XX Modalias: usb:v054Cp0306d0100
[CHG] Device 00:06:F5:9A:XX:XX UUIDs: 00001124-0000-1000-8000-00805f9b34fb
[CHG] Device 00:06:F5:9A:XX:XX UUIDs: 00001200-0000-1000-8000-00805f9b34fb
[CHG] Device 00:06:F5:9A:XX:XX ServicesResolved: yes
Failed to connect: org.bluez.Error.FailedI made a card with the old 8.2.2.3 image and BT remote and gamepad works.
I have done some OE hacking on the past to support another universal PS3 remote but I cannot bisect the problems here because I don't know where do you maintain your code.
Any hint ? I found that the BT and WiFi firmware are unchanged; the Bluez binary have different MD5 between images but that could be even a change on the compiler you used
TIA