[Ares301]

...Can be the battery, but the battery is only used to start the bike right? After the start the engine should provide energy for the system, right?...

Of course you right. It's not a battery.
Similar problem with DCT happened in U.K., Greece and Down Under.
And the problem was the same - gearshift drum shifter pin (in service manual - shift drum center bolt). Cost about $7.

 

[Ares301]

...Not true. ...

Just this moment on another forum, cattmando from Vincennes, IN is "reporting live" his process of repairing Shift Drum Center Bolt (Shifter Pin) which came loose. He's got hunch from this tread just yesterday.
There is Makman from UK Motorbike forum had broken shifter pin on his 2013 NC Integra, 21k miles.

There were guys from Australia, more from UK, Slovakia, Greece. That's only small part of owners.

You accuse others of lying about things you know nothing about.


No surprise that people don't follow up with their reporting when they're getting ignorant response like yours.

 

[Ares301]

..One person reports a shifter pin problem and suddenly everyone is having shifter pin problems. Another person reports a loose shift drum bolt ( completely different issue)...

Shifter pin (OEM part name) or shift drum center bolt (SM part name) are the same sh$t.

Do your homework or... who cares if you get it or not.

 

[Ares301]

2015 CTX700D with 25000 klms, went into limp mode (gear display flashing as "-")...
...I left my bike with the Honda Service Mechanics.

At this point, it's best to trust a Honda technician. They have specialized diagnostic equipment. First, they can read the Diagnostic Trouble Code (DTC) from PCM memory more easily than we can.