A handheld universal control with an OLED display

I previously made a universal controller, the 6-button "Pentagon", but it is not user-friendly. Not being able to memorize more than a few presses, it must be accompanied by a "Cheat Sheet". It is not a hand-held and many commands needed a two handed "Chord" multi-button combination.
This one always identifies the action. The up and down buttons select one of my 10 receivers, which is identified on the top row. The left and right buttons select the channel and command of that receiver for action. These are displayed on the lower row. The center button commands a transmission.
While off, there is no current draw. This device powers up by pressing the center button while off. While this button is initially kept pressed the display shows the temperature and battery voltage. The device automatically powers down within a minute after the last button press. While on the current draw is mostly due to the display, and varies with the characters. A typical value is 20 MA, so the batteries should last 2000 operations.
Major parts sources:
Keypad: AllElectronics.com KP-50
Display: NewhavenDisplay.com NHD-0216AW-IB3
Picaxe: SparkFun.com COM-10187
Transmitter module: SparkFun.com WRL-10534

Here are the circuit diagrams

Here is the code

This is the assembly which inserts into the wooden case in one piece.It comprises 4 sub-assemplies:
1. The keypad is surplus. It is a rubber-covered aluminum shell with a ribbon cable with one wire per button, plus a common wire. It has 4 long studs.
2. The main board is stripline. All of the other subassemblies plug inti it for easy servicing.
3. The display plugs into a raised extension of the main board so that its surface is co-planar with the keypad.
4. The battery holder is fastened to a piece of metal to use the keypad studs.

The antenna is Litz wire from a CRT yoke.