Second-hand iPad: Activation Lock and firmware error

Sorry, no. No-one can help (not even Apple), except for the original owner of the device. They would need to clear their account from the device to make it ready for another user. if they haven’t done that and you cannot contact them then the device is useless to you.

Unless you can independently obtain the assistance of the previous owner, the iPad is (and will remain) useless to you.

Here are the Apple support pages that outline the Activation Lock - and the only mechanisms by which it can be turned off:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Turn off Activation Lock – Apple Support

As you will discover, unless you are the owner of the AppleID that was last used to activate the device, you’ll not be able to defeat or bypass the Activation Lock. With documentary evidence that you are the original owner (such as sales receipt showing the serial number), Apple may be prepared to assist - otherwise they and nobody here will be able to help you.

The All Too Common SAD Reality of Buying … - Apple Community

Here is what Apple suggests when purchasing used a used (previously owned) device:

Check for Activation Lock before you buy a device from someone else

Before you buy an iPhone, iPad, or iPod touch, from someone other than Apple or an authorized Apple reseller, make sure that the device is erased and no longer linked to the previous owner’s account. Follow these steps to check if the device is ready to use: 

1. Turn on and unlock the device. 
2. If the passcode lock screen or the Home screen appears, the device hasn't been erased. Ask the seller to completely erase the device by going to Settings > General > Reset > Erase All Content and Settings. Don't take ownership of any used iPhone, iPad, or iPod touch until it's been erased.
3. Begin the device setup process.
4. If you're asked for the previous owner’s Apple ID and password, the device is still linked to their account. Hand the device back to the seller and ask them to enter their password. If the previous owner isn't present, contact them as soon as possible and ask them to use a browser to remove the device from their account. Don't take ownership of any used iPhone, iPad, or iPod touch until it has been removed from the previous owner’s account.

You will know that a device is ready for you to use when you're asked to "Set up your iPhone," “Set up your iPad," or “Set up your iPod” the first time you turn it on.

If you could return the iPad to the seller – and believed it was safe to do so – you could ask them to either

1. Refund your money, or
2. Prepare the iPad properly for a new owner (What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support), and then return it to you.

But you say that you "cannot get in contact with the original owner that had it."

That means you have a useless "brick". You cannot remove the Activation Lock, you don't know how to contact the person who can, and Apple will not remove the Activation Lock on the basis of a second-hand sales receipt.

Just to add some more information, to the already given correct answer by AKRBTN:

Activation Lock for iPhone and iPad - Apple Support