can a landlord accept partial cash payment after 3 day notice, and then Return it to tenant a few days later?? Does that void the 3 day not?

Once the partial payment is taken, the clock resets.

Some places I work a partial payment of any amount would void the 3 day notice (and the landlord would have to completely restart the eviction no matter how far along is was but landlord doesn't have to accept a partial payment either) but in most areas (that I work) the judge will simply amend the eviction from non-payment of say $1500 rent to non-payment of $1200 rent, or whatever (and they would even bump up the rent if more had become due).

So, I'm assuming you live in a place where a partial payment voids the eviction entirely (but again, usually it doesn't - at least not where I live). That being the case, if the landlord accepted partial rent I suspect that would stop the eviction. They must have realized their mistake later and returned the partial payment in hopes the eviction was not now stopped. My guess is, if they admit to the judge that they accepted the rent then the judge will toss the eviction and make them start over (otherwise every landlord who ever did this and went to court would simply return the paid rent right there in the courtroom) but I would be danged sure, as the tenant, to give them the money again, just in case. Slip it in their mailbox if you want.

However, if the landlord accidentally took partial payment, returned it and was then willing to simply lie to the judge and say they never were even given the payment, now the burden of proof is on the tenant to prove they did accept it so maybe this would not halt the eviction.

Just guessing here and guessing about something I rarely see anymore (again where I mostly work a partial payment no longer stops the eviction - only gets the amount changed by the judge) but its a somewhat educated guess.

A landlord NEVER has to accept late, or partial rent paymerts. No, it does NOT void the 3 day notice. The eviction will run its course.

If you failed to pay the full amount BEFORE the 3 day notice has expired, the landlord can legally refuse to accept payment and can choose to proceed with the eviction.

The 3 day notice would be void IF the landlord decided to accept any payment.

A partial payment is not paid & they still have the right to evict you. It would only void the notice if they kept the money. Since they returned it the 3 day notice remains valid. Clearly they changed their mind. Landlords are not obligated to accept a partial payment. They have the right to refuse anything that is not full payment.

A landlord can choose what they wish to do and you would need to ask the landlord your question................... however if you have been given a 3 day notice... that means PAY by the 3 days or LEAVE