I was told by a friend of someone with Five-O connections that Mrs. Freeman (whose husband created the original) first heard that the reboot was going into production "totally by accident."

The friend explained: "Somebody at CBS had mentioned it to her at some party or something, thinking she already knew all about it. She was furious that no one had talked to her ahead of time. By the time she found about it, filming had already begun, all the major decisions were already made. Legally, of course, they had no obligation to talk to her, but still. It would have just been the proper thing to do, to seek her advice and keep her in the loop ... What she did say was that [Ed Bernero, who was also going to do a reboot, which never panned out] at least ... had contacted her and asked her to look at his script. But Lenkov and company had just gone right into it, without a word to her. She was royally pissed off about that."

Despite this, Mrs. Freeman and Lenkov seemingly were pals afterwards, based on various things I have read.

More stuff of interest, from July 2015 discussion forum, posted by Vrinda (actually, reading forum archives is quite entertaining!):

It has also been said to me by different people that the producers of the new Hawaii Five-O don’t want the cast and crew of the new show to see the old show, going as far as to tell the actors not to watch the old show on DVD.

[snip]

These people from H502 said that when the show was first cast and being put together, the producers told the actors not to watch the original series because they didn't want the new show to be influenced by the original, citing it was going to be completely different and they didn’t want anyone pointing out the differences and trying to make it more like the original.

[snip]

These crew members also spoke of how guest stars from the original show who did guest spots on the new show were told not to speak about the original to the other actors. One person cited Robert Loggia, who talked about his guest appearance on the original and working with Jack Lord with the current show's actors and crew. The producers went up to him and told him to cut the conversation. For the record, he spoke fondly of his time on the original show.

And don't forget this, from December, 2011!

https://www.mediaite.com/tv/report-t...tery-ceremony/