I'm trying to factory reset it. How many hours or days should it take?

It is likely fully charged, so not charging. Turn it on and let it run down a bit.

This is normal. A factory reset sets the item back to the day it was installed by the manufacturer, no software you have installed or data. There is usually a warning before you proceed to tell you to make backups and ensure you have license numbers etc for the software.

sticking charger in to laptop as it may not have enough charge into erase the tablet iv had this problem before

http://www.rcatablets.com/how-completely-reset-your-rca-android-41-tablet try this.

It sounds like you've done most of the things you would reasonably be expected to do to make it function; since it is only 2 months old I would strongly urge you to go back to the retailer and make them replace it or refund you, as your rights in most countries/states allow.

If you're set against doing this, try holding down the power and volume down key for at least ten seconds to see if this boots it into hard reset mode. If this doesn't do anything, try again holding down power with each of the other buttons to see if you can activate any other developer/reset modes.

However, I have read reports that this particular tablet has up to a 40% failure rate in its first six months.

If you can possibly get it refunded, do that and buy something else.

Hi try this but follow each step very carefully.
http://www.howtogeek.com/130611/how-to-factory-reset-your-android-phone-or-tablet-when-it-wont-boot/

shutdown the phone then entre recovery mode and use those commands ( wipe data / factory reset ) and ( wipe cache partition

you could wait until a day but keep it on the charger because that happened to mine to

If you can get into the bootloader try doing a factory reset, if you are rooted press and hold the power and vol down button and that would boot into recovery. Worse case, you can google factory images for nexus 7 e and download a factory image from google and they provide the instructions on how to reimage your devices

you should press and hold the power button for about 10 seconds because you can't remove your battery while it hung and try to restore to the factory setting when it can power off
to do factory setting you can follow this step (restore to factory setting will erase all of your data going back to the first time you buy it)
1. press the volume up and power button at the same time
2. when you see the logo appearing release the power button but keep holding the volume up button
3. you can see displayed menu and use the volume up and down to select, then to reset to factory setting please select the option that labeled wipe data/factory reset using the power button