The Tmax is a great scoot, but I think these problems with the keys and keyless technology would put me off them for good, unless I could get a good Mk 3 etc. Like a lot of things these days, they seem to have to "improve" them year on year and many steps forward are actually steps back. I was thinking of getting another TMax, maybe next year, but think I'll stick with the Burger. Even the latest ones don't have keyless as I understand it.

Keyless is a great idea, but it never seems to be implemented very well, the the tech doesn't seem entirely reliable (and a nightmare if it goes wrong). As I've said before, with the Tmax, faffing around turning the key on and off seems to counteract any gains in convenience for the keyless system! On the plus side, on the Tmax its linked to the locking centrestand, which is a very neat idea. On the Honda Forza, I understand that the system will unlock the (Honda! Expensive!) topbox which would be handy.The Tmax system has never done that (even with a 'Yamaha' box) and thus means having extra faff of needing both the smart key and another set of conventional keys including one for the topbox. And Yes, I've ridden off with the topbox keys still in the topbox lock! Fortunately they were still there 20 miles later, but I wouldn't have made this mistake with a conventional system.

Problem sorted
I was thinking I might give it a shot and try with another new battery but different brand in the key fob. First was a Maxell one made in Indonesia but this time I’ve got the most expensive Sony one made in Japan.
And voila, magic!!!
Everything lights up and back to normal.
I’ve checked the voltage on the first battery (Maxell) and it was showing 2.8 volts. So that was more likely a new old stock.
The fresh Sony one (I carefully checked the production date on the package) was showing 3.29 volts.
So next time when you change battery in your fob make sure you buy quality one and fresh. It’s still cheaper than a coffee.
Thank you guys for all your comments and ride safe

Bizarre! My experience with batteries is that for my first replacement I bought an expensive Duracell battery - and it only lasted 6 months. After that I bought a cheap one from the Supermarket and it lasted well over a year! Maybe as you say its a question of how old the battery is, not the make or how much its been used.

Yep,

I have been having similar problems with my VW key fobs. Duracell batteries failed to work having bought them from a well known Internet selling site. They showed good voltage and I couldn't understand why they wouldn’t work. However under load they were failed miserably.
Screwfix’s own brand have been great ever since and never let me down.

I wish this post had been around a few years ago.