How to get it to do a new channel scan - Coby Electronics DTV102 ATSC StandardDefinition Converter Box

Impossible to answer without 'Make and Model', but we can guess.

Scan for what? Scan for new channels?

How to Scan (or Rescan) For Channels on Your TV

How-To Geek https://www.howtogeek.com > how-to-scan-or-rescan-...
Jun 19, 2019 - Find and select the "Channel Scan" option in your TV's menu. This option is sometimes labeled "Rescan," "Tune," or "Auto-tune."

Do you have an outside antenna? If so start scanning for individual channels at 000. Move 5 degrees scan for individual channels again. Move 5 degrees more. You must scan for individual channels. A wide range scan will erase everything else.
Go to Menu. Hit 7343 then mute. This should take you to a menu with a single scan option. It will take a very long time to complete this. Once you have scanned in every direction, be sure to NEVER hit the wide scan.

If when You scan, and you don't get at least one channel, it will keep showing You this message! look at screen it will show new channels! if no new channels check to make sure your coax is hooked up good, also make sure you are using right setting if outside antenna, select antenna, if cable select cable for your source!

Hello
To tune your Panasonic Plasma to on air TV channels do the following:

Connect the antenna connection to its antenna in at the back panel.

Automatically searches and adds available channels to the memory.

Select "ANT in"

Select Cable or Antenna Select "Auto"
Select a scanning mode

Auto channel setup
Select "Auto program"
Select "ANT in"
Select "Auto"
Select scanning mode (ALL channels/Analog only/Digital only

Start scanning the channels

Available channels (analog/digital) are automatically set.

All channels: Scans digital and analog channels

Analog only: Scans Analog channels only
Digital only: Scans Digital channels only
Confirm registered channels

If OK is not pressed after selecting "Apply", the channels will not be saved.

The channel will be saved when no operation is performed for 60 seconds and

the "Manual program" menu will also exit automatically.
If you perform scanning more than twice, previously saved channels are erased.

About broadcasting systems

Analog (NTSC): Conventional broadcasting

Digital (ATSC): New programming that allows you to view more channels
featuring high-quality video and sound
[Use "UP ' DOWN ' RIGHT ' LEFT] AND 'OK"] keys to selcet and proceed.

was it working before ?
Are you on cable ? run your scan in cable mode
Are you on an Antenna run your scan in air mode

Channel 8 is an analog channel . See if you have a diditial tuner , if so ,do a digital scan and that get you a version (8.1/8.2,etc) of the channel you are looking for

Buy a new TV

you may be able to do a manual scan ion each channel which is similar to auto scan.
Its normal for auto scan to select random channels when scanning.

Reset scanner by powering off, press the Hold,2 and 9 keys all at the same time and turn on the scanner.