Hi
the repairman said that he change CPU chip and License on my QRT5 board(it cost me a lot to do this ).
but I think he is lying because the device software id and Serial number and License key did not change.

He said he changed CPU chip and he gave me back the broken one with AR9342-Bl1a name on it but the install one is AR9342-dl3a.
is that possible?which chip installed on RB911G-5HPnD-QRT by default?

I don't know about serial number, but if it's like x86, software id would depend on disk (flash) and if CPU is separate chip, it should stay the same.

Software ID on RouterBoards depends on nand chip I'm sure about that.

License is based on the soft-id and soft-id is based on the set of components solderd on the router. If end-user tries to repair the router, then he is responsible for all of the consequences. For example, if you lose the license, you will not get any free replacement keys. If the router is broken, then you should return it to the seller for warranty repairs and should not ever try to repair the router for yourself. Please make sure that you select RouterBOARD seller not based only on the price, but also on the offered warranty terms, assistance with configuration, etc. If the router is repaired by MikroTik or distributor then you should never receive a router witout RouterOS license.