Chainrai appeared to have distanced himself from the financially-stricken League One club when he pulled out of a takeover bid last week.
However, Chainrai performed a U-turn, saying that he hopes to complete a takeover in the next two weeks, and he has now taken the first step to doing so by submitting a new offer.
"Portpin has submitted a new offer and we are now reviewing it," read a statement from the Portsmouth administrators.
"We have been working with the Trust since Portpin's original offer was withdrawn and understand that the Trust is on track to submit a business plan and revised offer tomorrow.
"We will assess its bid once it has been submitted and will then determine which offer provides the best deal for creditors, as is our duty as court appointed administrators."
Meanwhile, Portsmouth's on-field duties resume away to Carlisle on Saturday.