Why is that after the battery gets down to about 15% or after I've used it for a while, it decides to shut off and it won't let me charge it back up. I plug in the charger and the screen stays black but I move the charger and it shows me a battery with a yellow yield sign on it and then the screen starts changing from black to white and there are lines everywhere like the screen won't load fully. I only got this a couple weeks ago and it only started having problems a day ago.

Help My tablet won turn on what do do

Why Does My Android Phone or Tablet Not Turn On

Patricia, Using the power switch, you can forcibly reset your Kindle device. This reset will shut down the Kindle without accessing the shutdown command from within the Kindle's operating system, a particularly useful tool when dealing with a frozen Kindle. To initiate a hard shutdown, Kindle disconnect from its charger, slide and hold the power switch for about 20 seconds. This will force the Kindle to shut down, now it can be restarted normally.
Check links below for charging problems.
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You neglected to provide the age of the tablet. If it's a couple years or older your battery might be on the way out. They don't last forever and some of them aren't of the best quality to begin with. Charge it all night long. In the morning when you turn it on if it still doesn't work right be sure to check the battery level with the A/C adapter unplugged. The level indicators are based on the voltage. If the voltage doesn't come up to spec, it might show less than 100% charge even when charged overnight.

The wi-fi problem could be battery related, too, as wi-fi is a radio transceiver that sends as well as receives signals. Wi-fi doesn't work so well if the transmitter produces a weak or intermittent signal.

Have you checked to see what the battery percentage is at when it shuts down?

Make sure to give it a really good first charge, and don't play any games while it's charging and low on power. Many of these new and intense games can actually kill the battery faster than the charger can charge it.

I think it is time for a new notebook

This tablet does t reset with the power button unlike other Android devices. When you hold down the on/off switch, it only drains the battery. If you see the color indicator still charging, allow a full charge.Then, only stay put and pulse the button for a moment quick and let it rest few seconds to try again and again. Only when u see a light coming out of the screen, and I recommend you do this with the power cord on, you hold the power switch down until the rebooting is iniciated. Let go til it is finish and see where the problem is. More likely, like mine, the Settings stop working and needs tune up for the CPU. Never leave an application running when closing your system. With or without internet connection.

hardware issue i think

try to hard reset or soft reset, for this procedure search on gogle.com how to reset tablet, that will be helpful.

It sounds like your in sleep mode. Hold the power button till the display says power off and tap the power off on the display, the charging light will come on and the charging light will change color when it is fully charged. Here is the link to the pdf quick start guide:
http://www.pandigital.net/userfiles/file/Downloads/QSG_%20PRD07T-1_v2.2_09-08-10.pdf
Hope this helps thanks for using FixYa