Invalid mmi code

I have the HTC One m8 phone. Every time I try to type in a code on my dialer it always shows, (invalid mmi code). I've tried several ways but I still can't get it to work. I was trying to enter secret codes for htc, as an example. Does anyone have a solution to this. And I don't have a PC
Dwayne MichnalAsked:
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Jackie Man IT ManagerCommented:
Have you tried the one below?

Phone information and testing menu
*#*#4636#*#*

Source: http://droider.eu/2015/04/18/secret-codes-for-your-htc-phone/
Jackie Man IT ManagerCommented:
What is the problem with your phone and what do you want to do with the secret code?
Dwayne MichnalAuthor Commented:
It's not so much secret codes. It's just about any codes that I try to enter. One of them that I was interested in was trying to go to hardware section to go to audio so I could increase my factory volume settings. I can't remember what it was but there was an app for that but my phone didn't support it
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Jackie Man IT ManagerCommented:
One of them that I was interested in was trying to go to hardware section to go to audio so I could increase my factory volume settings.

From my experience, you need to root the phone if you want to increase my factory sound volume. No change can be made via settings or secret code.
Dwayne MichnalAuthor Commented:
The code I was trying to enter was *#*#3646633#*#*
Jackie Man IT ManagerCommented:
The code I was trying to enter was *#*#3646633#*#*

The above code is for enginering mode for Acer, Infocus and other andoroid phone running MTK CPU. Your HTC M8 will not understand this code and it is normal that you will get a reply with "invalid mmi code".

http://www.techbang.com/posts/24356-android-cheat-open-mystery-works-on-a-mobile-phone-model-major-brand-password-overview

For HTC, the secret code is:-

*#*#4636#*#*
Dwayne MichnalAuthor Commented:
Thank you very much for your time and help. One last question. How can I root my phone in one step that will install everything I need to do it without having to zip files and etc without a PC
Jackie Man IT ManagerCommented:
Rooting is not a topic for discussion here.

Anyway, the one step rooting which I have tried with a success is with Kingroot. I have tried to root a LG phone running Android 4.2.2.

https://kingroot.net/

Rooting can brick your phone easily if you are not knowing what you are doing.

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Dwayne MichnalAuthor Commented:
Thank you very much. I'm glad I had the chance to chat with you. I do appreciate your wisdom. Have a good one buddy
Jackie Man IT ManagerCommented:
It is my pleasure to help.

Good luck.
Jackie Man IT ManagerCommented:
Any further question?

If no, you can close this question.
Jackie Man IT ManagerCommented:
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