calculator顯示不清楚,有解決方法嗎?(urgent!!)

I am not convinced this is a low power (battery replacement) problem. The fx-50F is a dual-power model (solar panel and button tyoe battery) and the lithium button buttery has a very LONG runtime. If this battery runs out of power, you won't be able to use the calculator under low-light conditions, and the WHOLE display will get dim.
But in this case, you said 第一個數字好像有點褪色, which means the LCD panel itself is getting faulty. It could be one of the following problems:
a. The inside of the LCD panel has become oxidised to certain extent after VERY long use, that the segmented digits cannot be displayed properly anymore. With this symptom, the display usualy can't produce SOLID DARK numbers etc. and the colour becomes (sort-of) dark rusty red;
b. There are certain contact problems (or other problems) that render the display faulty, again resulting in displaying 断字.
In either case, the entire LCD module must be replaced. In the case of calculators, repair costs could be highter then expected. This can happen to watches and clocks too, and repair depends on the availability of the parts.
A calculator/watch/clock that has symptom (b) can be fixed temporarly without replacing parts, but the problem will return after time, which means the whole module MUST be replaced.
I suggest you take back the calculator to either Onflo or Multi-M for full diagnosis. If the LCD module needs to be replaced, ask them for a price quote. If the repair costs are indeed too high, then you are better off getting a new calculator model.

如果無估錯, 你之前有無攞過舊電出來呀, 如果係，咁就去d文具店買啦!(幾蚊), 因為可能用太陽能嘅時候唔夠光。
但係睇你呢一個都幾old下bor，不如轉過部新嘅啦!希望幫到你!^^