i2 Info Key and starting up issues just appeared

[i2Macman]

I have a 2006 i2 PT which has been on charge over the last few years; I use a timer to switch off the charger for about 8 hours per day.
I use the Seg intermittantly around my yard- no problems. The batteries remainded fully charged except for the ½ hour intermittant exercising. Then back on charge.
A few days ago I went to execise it again but discovered my info key was reporting a low battery on the screen everything else was not holding settings.
So, got my spare infokey - it was reporting low battery as well.
Managed to get the i2 started all was well full Seg batteries reported ( two lights blinking green when removed from AC.
Rolled around a few metres but could not go over 3km/hr without getting a exclamation mark and a flat smiling face, then stick shake; slowed up to 0.5km/hr all was well. But unable to go any faster.
Hmm, I relpaced the two info key batteries. Batteries measured 3.56 volts, so thought they would be fine. On installation and during start-up both info keys seemed to indicated the new batteries were near flat. Persisted with start-up and glided again. Same outcom:e super slow speed, stick shake and flat face.
Inspected Segway no apparent damage, no errors display at all, no gilding obstacles or bumps, handle centred and tight, batteries not loose.
Hmm, put two now batteries in the info keys again, 3.6, 3.2 volts before installation. Again on both keys during start-u,p the rapid infokey battery display suggested these two batteries were near flat too. Keys now hold settings , no turtlemode active.
But still unable to ride without same problem. Removed both batteries swapped positions. This did not change any behaviour; when stared up both batteries show full chage.
Stumped, I am now discharging both batteries and will recharge them but wonder if I have two malfunctioning info keys or a radioboard fault but no error codes showing at all. Just super slow speeds and stick shake and shutdowns.
Start-Up is a little more effective if within 1-0.5m from console. I have searched the forum and carried out all tasks that appear to relate to my issues but without resolution. My issues are partly covered by a range of individual posts but none fully.
Any thoughts relating to these issues would be appreciated.
Thanks for your comments in advance.