"ㄌ" and "ㄡ" are both Zhuyin, the phonetic symbols used in Taiwan, you're right.:) In the sentence, "ㄌㄡ" is informal written, it replaces "了喔" (we say "了喔" sound like "ㄌㄡ"), just like using "U" instead of "you". I say "按了喔" to you may means to tell you "I already pressed it." or ask you "I press it, alright?". And "了喔" is like something added to the end of a phrase (just like Liv said).

BEAR IN MIND THAT IT'S 國 ㄍㄨㄛˊ 語 ㄩ ˇ 注 ㄓ ㄨ ˋ 音 一ㄣ 符 ㄈ ㄨ ˊ 號 ㄏ ㄠ ˋ, NOT 日本語.

見 中華民國教育部 國語推行委員會 國語文教育叢書第42種 國語注音符號手冊 http://www.edu.tw/files/site_content/M0001/juyin/index.htm 又見 維基百科 注音符號 http://zh.wikipedia.org/zh-tw/%E6%B3%A8%E9%9F%B3%E7%AC%A6%E8%99%9F 或 http://en.wikipedia.org/wiki/Bopomofo 範例 請見 中華民國 僑務委員會 全球華文網路教育中心 華語 - 初級 - 幼兒學華語 - 兒歌 教本http://edu.ocac.gov.tw/lang/basic/ch_preschoolers/nurseryRhyme/01htm/001-c.htm

hi, 按 is Chinese, its pinyin is a, BUT ㄌㄡ is Japanese. the Japanese characters are rooted in Chinese. so you mistake them. then in Chinese, ㄡ can be as radicals of a character. etc. 汉(ha), there is one ㄡ in it. in fact, it's 又 (you), it looks better than Japanese ㄡ. :-)

It is not Japanese, it is Chinese. 按 (an) is "press" and ㄌㄡ(lo) is just something you add to the end of a phrase. The whole thing means "press, alright~?"