MacBook Pro 2015 Bluetooth utterly unresponsive

<< hold the Shift + Control + Option + Power keys for 10 seconds. >>

Your simplified version of SMC reset is NOT adequate. Readers MUST use exactly the correct keys, and exactly the correct timing of key-presses, or NOTHING happens.

Reset the SMC of your Mac - Apple Support

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It also might work if you reset the SMC, you can go HERE to see how to do it for your model.

Please run an EtreCheck, and then copy and paste the report here using "Additional Text"

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I edited it

good recovery!

Sorry, I've been doing physical Apple repairs for so long, I'm not used to this! Hope it helped.