Why Mobile Phone Turn On In Software

I am newbie in flashing field and I am facing one problem with various mobile phones. After turning off phone when I try to attach phone with Volcano using USB wire or with similar device to read info or writing flash file or anything else when I try to do, mobile turn on and sometime start charging and don’t allow me to do anything in software. 😡

I will be tremendous thankful if someone tell me why this happen and what is solution of this problem???

Thanks In Advance… 🙂