Tv turns on and off all on its own sometimes it even acts like it totally loses power and starts doing a channel search

Sounds like a power phase issue.

I purchased an LG43UN7100 just before Christmas 2020. It has used the same aerial connections (ports/cabling) previously used by both Samsung and Philips televisions, which worked perfectly. After twelve days of use, I've now retuned it 4 times and have even followed advice to disable the Quickstart Plus and reset back to initial settings. From an internet search I suspect that this is a common 'feature' of LG televisions :(

Remove the batteries from the remote then see if the set returns to normal and you can use the buttons on the tv. If after the batteries are out and the set is still acting upreturns back to normal then the remote is bad, I have seen cases where something has been spilled on the remote and no one was told.

u have to replace memory ic...

When you are turning the recorder on it is blocking the signal for cable going to the TV. Your TV will need to be on channel 3 or 4 depending on what the dvd/vcr player channel output is set to. This is why your tv is asking you to re-scan. It is losing the video signal because the dvd/vcr is taking over. The reason why the vcr with the button on the remote is because the vcr button is changing the function of the buttons on the remote to vcr. Even though the dvd/vcr is one unit they still will act like two seperate components independent of each other. They have seperate power buttons and the dvd player part may need to be hooked up seperately with rca cables to work.

The User Manual for your DVD Recorder is available here... http://www.p4c.philips.com/files/d/dvdr3380_05/dvdr3380_05_dfu_eng.pdf

Info related to your specific problem is as follows...

Setting your TV channel
programmes
Before the recorder can start recording
the TV channel programmes, you need to
search for the available TV channels and
store them in the recorder.
Note: Make sure you have successfully
made all the required connections to the
recorder, the TV and Satellite Receiver/
Cable Box (if any) and switched them on.
Tuner settings can only be changed
when there is no disc in the disc tray.
A Press SYSTEM-MENU on the remote
control.
�� The system menu appears on the TV.
B Use ���� keys to highlight
{ System Menu - Channel Setup }
and press ��.
System Menu - Channel Setup
Modify Channel Information
Sort Channels
Channel Search
Edit
Sort
C Use ���� keys to highlight { Channel
Search } and press OK.
�� The automatic TV channel search
starts. This process may take several
minutes. Once complete, the total
number of channels found appears on the
TV.
Automatically scan all the receivable analogue local TV
channels and store these channels on the recorder.
�� Use ���� keys to highlight { Channel Search } and press OK.
�� The automatic TV channel search starts. This process may take
several minutes. Once complete, the total number of channels found
and stored appears on the TV.
Modify Channel Adjust a stored TV channel to your preference, improve the
Information reception and the sound quality of that TV channel.
1) Use ���� keys to highlight { Modify Channel Information } and
press OK.
�� The channel menu appears.
2) Use ���� keys to select one of the options.
{ Name } – You can use the numeric keypad 0-9 to select
the channel preset number which you wish to
change.
– Use ����keys to change alphabet/ number and
use ���� keys to select different entry fi elds, then
press OK to confi rm.
{ Scan Mode } – Select TV channel search mode based on
channel allocation or frequency.
– Use ���� keys to select { Frequency },
{ Channel } or { S-Channel } (Special Channel),
then press OK to confi rm.
{ Frequency } – Shows the frequency of the current TV
channel.
– If required, use ���� keys to start the automatic
frequency search and press OK to confi rm.
{ TV System } – Set the TV system that produces the least
distortion of picture and sound.
– Use ���� keys to select a suitable sound mode,
then press OK to confi rm. (See chapter “TV
System Guide” at the back of this manual for
more information).
{ NICAM } – Turn on or off the digital sound transmission
system which improves the sound quality of the
TV channel.
– Use ���� keys to select { On } or { Off }, then
press OK to confi rm.

Sounds like The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

What brand of tv is it ? You could have a bad tuner or a change in the voltage supply line feeding the tuner . What type of antenna do you have ? outdoor or rabbit ears ? Also does it retain the channel line up or does it clear them as well ?

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