Shortcut on OTG cable killed my batterie?

I crafted an OTG Kable my own and it worked fine with my PS3 controller. I then wanted to load my iPhones batterie but the cable was broken so a lot of times on pc/mac it says :" Your device draws too much energy". Thats becaus of a shortcut. I don't know what was shorting but i gues it was the + and - 5 Volts line. You could even see sparks when i tried it on my PC after!

So of course the phone wasn't powered. nothing happend.

When i look at my tablet a few days after it was completley DEAD. Nothing. to even the smal light at the bottom. I hocked it up to load the batterie and it took really long until it finally showed some life signals.

But the batterie is empty within 2 days without usage in airplane mode!

Somewhere is like a resistor with a shortcut drawing batterielife all the time. A friend of mine installed a custom rom with undclocking and undervolting etc. it got a little more to the lifespan but not really good.

And now it won't turn on anymore :(

What could this be? Maybe this? : Nexus 7 (2nd Gen Wi-Fi) Volume and Power Cable

Do you think i can open and watch for burned parts?