Get kw-nt500hdt out of demo mode

First, I'm not a JVC representative.
* Check your warranty. Call for support
* Contact; Website(includes manual); http://support.jvc.com/consumer/product.jsp?modelId=MODL029018
* Support; http://www.us.jvc.com/support/car/

*** The following is for information only.***
* Manual; https://pdf.crutchfieldonline.com/ImageBank/v20120222140500/Manuals/105/105KWR800B.PDF
* See page 4 step 3 to turn off.
* Perform Reset (page 3)
* Bad button(s). Your front display and control panel may need to be replaced.
* You may need to upgrade to current firmware. (contact to install)
* Demo (official); https://www.crutchfield.com/p_105KWR930B/JVC-KW-R930BTS.html?tp=5684&awkw=373095005473&awat=pla&awnw=g&awcr=226791677002&awdv=c&awug=9032739&gclid=EAIaIQobChMIpauyp8jZ3AIVi_5kCh00cwfyEAYYASABEgK3I_D_BwE
* Amazon (note: question option); https://www.amazon.com/JVC-KW-R800BT-Stereo-Receiver-Bluetooth/dp/B0079LGMB4
* Call JVC support 1-800-252-5722 for additional advice.
Aloha, ukeboy57

Buy a map ?

IF you have 2 disks stuck in it you are not going to be able to remove them without damage unless you take the unit apart.

Do a reset to this TV and check. If it do not help you, contact any service technician. There are two types of reset to TVs. The first is simple to do; a Hard Reset. The other is somewhat skilled; is a Factory Reset (System Reset). To make it a hard reset, just unplug the TV from AC mains wall socket, and re-plug it back after 15 minutes or so. If you do this by overnight; will be better. This procedure will make it a hard reset. If you want to make it a system reset [Factory Reset]; you have to enter its service mode option, and select the factory reset option. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/
Service mode entry, adjust and exit procedure to many popular brand TVs are given. Never forget to exit the service mode, after all adjustments have been done.

You most likely have the 12 volt permanent connected to the switched supply lead you need to identify which wire requires the permanent and the wire that requires 12 volt switched this will only appear when you turn your car key to acc position , it's normally a yellow or orange wire your looking for but check your models schematic.

Press Menu on tv remote, go to Settings and select Factory Reset and press enter button on remote, tv will reset to factory default settings and turn Off and On again itself, now select HOME mode instead of Shop mode to avoid demo mode and go by initial setup screen instructions.
Above are generic info about Sony bravia tv, let me know model number of your tv if you do not see factory reset option in settings menu.
Thanks.

First reset it to factory default: While pressing [^] button on the remote, press [Power] button on the TV.
Second software update, Click on http://esupport.sony.com/US/perl/swu-list.pl?mdl=KDL42V4100&LOC=3#div_pos_30. For further information, please add you commend.

DEMO MODE ON/OFF
Demo mode is designed for retail store display. In this mode, the oven can be demonstrated with no power in the oven.

On the "Timer/Clock: button:

4 taps ON The oven is in Demo mode.

4 more taps OFF The oven is not in Demo mode.

You can try reseting to factory default as per the manual. See picture below. Please update the question & let us know if the information given was useful to you - Good Luck!

take your set to tech to repaired you set is having a memory problem that you cannot solve.good luck.greetings from belize.