My device muscle stimulator cefar is always in standby mode what to do?

It depends on how much extra voltage you put into it. It may be repairable. This appears to be the maker, but not sure. They say a 3 year warranty on it.

https://guatemaladigital.com/Masajeadores+el%C3%A9ctricos+-+de+pies/ProductoP/B07ZXQXSF3

https://www.google.com/search?q=Osito+Muscle+Stimulator

..

https://www.google.com/search?q=RS+medical+stimulator+RS-4i+battery&rlz=1C1CHBF_enUS757US757&oq=RS+medical+stimulator+RS-4i+battery&aqs=chrome..69i57j0i22i30.4688j0j4&sourceid=chrome&ie=UTF-8

Once may mixed your own training, you'll learn with regards to third leg of the muscles fiber stool - another third of muscle fibers which cannot be stimulated through conventional practice. To access them, you'll to choose a way to boost your 5-ATP chemical levels, or the fuel that permits your muscles to rail. The more 5-ATP you have present on the inside muscles, a lot reps you'll see with more weight, each set!



http://testosteroneboosterreview.net/testadrox/

Once may mixed your own training, you'll learn with regards to third leg of the muscles fiber stool - another third of muscle fibers which cannot be stimulated through conventional practice. To access them, you'll to choose a way to boost your 5-ATP chemical levels, or the fuel that permits your muscles to rail. The more 5-ATP you have present on the inside muscles, a lot reps you'll see with more weight, each set!



http://purelifegreencoffeebeanadvice.com/testadrox/

How do you open the ACU xp ISMART to put in the battery

The beep is mandatory and a safety feature. It is also used for warning of malfunction. This is a medical device and you may render it dangerous by removing the internal sounder. I cannot recommend removal of sounder although i can see no reason why you could not quieten it with a little tape over the holes as long as it can still be heard.