Your batteries are either no good, or not charged. When you press the PTT button it takes more energy than being in standby mode. If you have a battery problem it will fail quickly when the PTT is pressed.
Rechargeable batteries last approx. 18-24 months. Check your battery for a 3-digit date code. It is usually a 3 digit number followed by a couple of letters. The numbers tell the date of manufacture. The first number is the year, followed by the week of the year. 025 would be 2010 the 25th week. (or if very old it could be 2000 the 25th week.)
If you feel age is not a problem, you might check your charger(s) to see they are fully powered, and clear of debris on the contacts (and the radio contacts as well). Clean with a pencil eraser if needed.
A few tips: Be certain when placing your radios on the charge they are turned off. Check your wall outlet to be certain it doesn't get shut off with a light switch. Expect to replace your batteries every 2-3 years.
Use scanning to monitor channels for transmissions or to find someone
in your group who has accidentally changed channels.
1. Short press MENU until the "Z" appears. The current setting
On/Off will flash.
2. Press either + or – to turn On or Off.
3. Press the PTT to confirm or MENU to continue set up.
Here is a link to the manual http://www.motorola.com/mdirect/manuals/FV200_userguide.pdf
Tis a problem you have there, however I would advise you take one of your radios to radioshack or similar store, and the folk there should be able to assist in finding the apropriate chargers for you.
I hope this helps you in your quest.
This one should be a very close match. The T4508 is a foreign version of the T4500.
The Motorola GP340 radio is a dealer programmable radio. It requires a cable, radio interface box and Motorola proprietary software (which is available by subscription to dealers and qualifying entities).
You will find the manual here. The radio is part of the 280 series radios, so there is a general manual on all in that series.