As this is just a forum its difficult to point you to a technician. i’ve checked the HP website and they don’t have a service guide for the printer your talking about they might have one on hand if you contact them. other than that you may be able to look online somewhere for a teardown. if you upload some images I might be able to help too !
Sounds like you may have damaged the sleep sensor, When connected even though the display is open your MacBook thinks its closed and the screen turns off you could test this theory with InsomniaX, this will make your Mac think the lid is constantly open regardless of the sensor. https://www.macupdate.com/app/mac/22211/... If it is the sensor as far as I know they are attached to the keyboard and it cannot be replaced on its own.
To be on the safe side first do a PRAM reset and an SMC reset. If this doesn’t work are you able to boot into network recovery on the internal display? This will rule out a software issue. See this guide on booting into network recovery: https://support.apple.com/en-gb/HT204904
Firstly you need to disconnect the battery this is key. although its switched of there is still power flowing through it. although there isn’t a guide specifically for this you can follow the teardown to step 6 which will show the battery disconnection process. if possible keep the screen separated from the keyboard or place a thing cloth between as when upside down water can leak into and behind the glass ruining your screen too. Once disconnected if you are able to yourself you will want to fully tear down the machines as best you can and follow this guide . you will need to clean the boards with isopropyl alcohol. This will work best to try and clean up the corrosion from the water. although before you switched it off you only had an issue with your speaker corrosion will work overtime to render your laptop useless.
Rather than just pressing the sync button on the controller, with the controller switched of press the XBOX button and the sync together and hold it until the light starts pulsing then press the sync on your xbox one console,
First try resetting the SMC if you haven’t already. if you have no luck with this download and install coconut battery and post the information back here. https://www.coconut-flavour.com/coconutbattery/
The HDMi Port is soldered to the main board there is no easy fix for this unless you are able to solder, Have you tried another HDMI cable ? If that dosnt’t work try cleaning the port with a cotton Bud and some rubbing alcohol if you have it.