They did more than investigate. Nokia, at that time still market leader in mobile phones, wasted a lot of time and effort because management wanted them to move to Intel. Nokia engineers did not believe that Intel would ever reach the required power efficiency. Whether it was self-fullfilling prophecy or just technically impossible is anyone's guess. (No, Nokia did not fail because of Intel, but that miss certainly made the disaster more complete.)
Intel connection was not the sole reason for Nokia's demise in phones, but it contributed on the failure of their effort to recover from the tailspin. Symbian their old mobile platform was clearly due to be replaced and they had a pretty viable in-house Linux platform, Maemo, that already shipped with N900 in 2009. Instead of iterating on that, they decided to "join forces" with Intel and merged Maemo with Intel MobLin to create MeeGo. They wasted at least a year on that and not with a lot to show for it as the Intel chips they planned for never materialized.
Obviously it was going to be very difficult to compete as a third platform with the behemoths iOS and Android become during those years. At least the MeeGo and Windows Phone cards were not the winning ones.
That's the software part of the story, which became fully public in form of MeeGo.
But there was also a hardware story how Nokia would start Intel silicon. I don't think anything of that has ever been publicly annouced before it failed. Wasting a year seems to be massive underestimate. I believe it must have been much longer. After Nokia started to fail Intel hired former Nokia engineers. I have no reliable insights what they did there, but I believe at least in the beginning they still worked with phone hardware on low-level software.
