Volume won't go up

Already answered

Yes, buy a remote control :>) They are readily available, no need to program and can be obtained from Amazon, eBay and specialty remote retailers like www.remotes.com

Google

Seiki (model) replacement remote

https://www.google.com/search?q=seiki+tv+replacement+remote

The most likely reason for your issue is a dirty button and the contacts. Switch Contact Cleaner may fix it.
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two choices, get the keyboard on the set repaired or get an original sharp remote which among remotes is not too expensive.

Some sound bars have a seperate power cord, did you plug it in. Also, the source for the sound, are you using the audio outputs and not the audio inputs. They are all the same color (red and white) so you may have plugged in the wrong ones. If the sound bar is getting power, say a green led and the source for it is the tvs audio ouput jacks you might have to see if there is a seperate remote for the sound bar and raise the volume. Lastly the tvs audio output might have a seperate setting, it could be fixed or variable. Fixed will only change volume with the sound bar remote. In variable you will be able to change the volume with the tv remote but first you have to raise the sound bar level. Hope this helps in some way.

1. Find the 5 & 12 or 9 v line caps. Try to replace electrolitic caps.
2.Find out the keypad pin from the processor and suck it. Then use only remote.

Try this.....

Turn cable remote volume all the way down. Raise the volume all the way up with your TV remote. Lower the volume with Cable remote to your usual listening volume.

Open the thing up and clean off all the dirt on the volume buttons with a dry rag and clean the remote sensor.  Put in fresh batteries and now give it a try.

Without knowing the model number it's hard to say. However, it's not uncommon to have a defective switch on the actual TV itself. Try pressing the switches on the TV and make sure that they 'snap' in and back out when they are pressed.

resorted contacts on bottom of control board.

Use the satellite receiver remote control to adjust the volume first. The receiver itself offers volume control and you probably have that turned down. Then you are trying to raise it with the volume control on the TV. This is raising the TV volume, but there isn't much sound there in the first place. Use the receiver remote, and you will probably see a volume bar. At some point it might say something like "best stereo" or a star might appear. If that happens leave the volume set there, otherwise just raise it all the way. Then control the volume with the TV remote, or program the DirecTV remote for your brand of TV, and the volume button should control the TV then.