[heero_yuy]

Here's something interesting:

CEC

Consumer Electronics Control (CEC) is an HDMI feature designed to allow the user to command and control up-to 15 CEC-enabled devices, that are connected through HDMI,[63][64] by using only one of their remote controls (for example by controlling a television set, set-top box, and DVD player using only the remote control of the TV).[65] CEC also allows for individual CEC-enabled devices to command and control each other without user intervention.[65]

It is a one-wire bidirectional serial bus that is based on the CENELEC standard AV.link protocol to perform remote control functions.[66] CEC wiring is mandatory, although implementation of CEC in a product is optional.[49] It was defined in HDMI Specification 1.0 and updated in HDMI 1.2, HDMI 1.2a and HDMI 1.3a (which added timer and audio commands to the bus).[65][67][68][69][70] USB to CEC adapters exist that allow a computer to control CEC-enabled devices.[71][72][73][74]

Trade names for CEC are Anynet+ (Samsung), Aquos Link (Sharp), BRAVIA Link and BRAVIA Sync (Sony), HDMI-CEC (Hitachi), E-link (AOC), Kuro Link (Pioneer), INlink (Insignia), CE-Link and Regza Link (Toshiba), RIHD (Remote Interactive over HDMI) (Onkyo), RuncoLink (Runco International), SimpLink (LG), T-Link (ITT), HDAVI Control, EZ-Sync, VIERA Link (Panasonic), EasyLink (Philips), and NetCommand for HDMI (Mitsubishi).[75][76][77][78][79]

Wiki

It would appear that if the TV set has this feature and it is enabled then remote equipment could put the TV in standby via the HDMI. Probably find the OP didn't know about this and the tech just turned this feature off. (Shhh, it's the TV)